Prusa i3 MK2(s) & MK3 Spool Holder - Frame Mount - Top Loader

by MartinMajewski, published

Prusa i3 MK2(s) & MK3 Spool Holder - Frame Mount - Top Loader by MartinMajewski Oct 22, 2016


Update: As the Beta 5 of the Mark 3 arms show to be functional and easy to print they reached the final status. Therefore, when you have a Prusa i3 MK3, use the Mark 3 arms. All other parts can be reused from the Mark 2. Maybe I will rename them in the future to make the download section more homogeneous.

Right after l got the Prusa i3 MK2 up and running, I noticed one major flaw of that otherwise fabulous machine:

The spool holder!


Not only that it looks not as well engineered as the other parts of the machine, but it is also not very convenient regarding usage. Especially if you want to do layer based color printing you have to switch the filament quite often during one print. Bending the original spool holder to release the mounted spool, as well as adjusting it to hold the new one in place (mainly if the spools width differs from the first one) is time-consuming and tedious.

There are already a few alternatives here on Thingiverse, but after trying a few of them out, I found that they have some other issues.

  1. Their wheels are often mounted using printed hexagonal screws (bolts) and nuts. This results in the need for tools like a wrench to tighten them up.

  2. The mounting to the metal frame of the Prusa i3 MK2 is often not well designed. Most of the alternative spool holders rely on pure force to clip the holders onto the frame. This has two consequences:

    1. The required force is not good for the printer's construction, nor the printed parts, that can easily break (as happen to some of the spool holder arms I printed).
    2. It makes adjustment for other spool widths very hard.

  3. If the extruder reaches a certain hight on the z-axis it could crash into the overhanging construction.
So I designed this spool holder, where the spool is laying on four wheels that roll smoothly on 608 (skater) bearings and hopefully eliminating the foregoing drawbacks. Speaking of which, ...

  • ... it is an all tool-less design. All parts are just slid into each other. The nuts can be tighten by hand.

  • ... the arm's clamping design is optimized for an easy attaching onto and detaching from the printers metal frame, with as little strain on the parts as possible. This makes also the width adjustment very unproblematic and fast.

  • ... due to the small footprint of the holder's arms, you can mount two spool holders side by side.

For arms that fit other frame sizes please take a look here:

Your opinion on this design and suggestions to make it even better is appreciated
Please also take a look at my other designs, printer parts, and tools.

If you like to support me and my work, please consider to follow me

Sending a tip over Thingiverse will buy me some coffee to stay productive. :-)

Thank you very much.

Print Settings


Prusa i3 MK2






0.2 mm


10% for all small parts, 20% for the arm.


You'll have to print the following parts in the following quantities.

First off, choose an arm version:

  • For the Prusa MK2(s) or MK3:
    1x Mark3_SpoolHolder_HexStyle_ArmRight.stl
    1x Mark3_SpoolHolder_HexStyle_ArmLeft.stl
  • For the Prusa MK2(s) only:
    1x Mark2_SpoolHolder_HexStyle_ArmRight.stl
    1x Mark2_SpoolHolder_HexStyle_ArmLeft.stl

Then the rest of the parts:

  • 4x Mark2_AxisScrew.stl
  • 4x Mark2_AxisSpacer.stl
  • 4x Mark2_AxisNut.stl
  • 4x Mark2_SpoolHolder_HexStyle_Tire.stl

Optionally you may want to print the SpoolHolder_HeyStyle_PressingHelper.stl to press the bearings into the printed tires.

Note: users have reported that the bolts are breaking easily during the assembly. To avoid this from happening I highly suggest that you print them with 100% infill!

To make the spool holder work, you need four 608 bearings for one set, which you can get from a local skate shop or from Amazon (by using the provided links you can support me and my work):

You often find eight bearings inside a set, which is enough for two spool holders.

The spool holder is designed in a way, that you can use all parts of both sides of the holder and also switch the axis screws from back to front and vice versa. If you like to have the "smooth bed side" oriented to the outside, you have to mirror the right arm along the x-axis.

For the infill, I used a honeycomb pattern because it matches the hexagonal style of the holder and my filament is quite translucent. Honeycomb gives good mechanical support in general.

I printed three perimeters for all small parts. Four parameters were used for the arm and six perimeters for the wheels to avoid infill there. Each part has four top and bottom layers on my prints - except for the arms, where I printed without any top and bottom layer to achieve the honeycomb look.

Even though I printed my final design in 200µm (0.2 mm) layer resolution, I also tested 100um (0.1 mm) for the wheels. That gave them a smooth finish, but it had no effect on the mechanical properties.


Screws and nuts...

The screws and nuts should fit nicely with a small clearance. Nevertheless, it can be hard to get the nuts screwed onto the bolts the first time. So give them a gentle press and try to find the sweet spot where the threads match up.

For the Mark 1, I used a small amount of PTFE grease on the threads to make handling easier.
The Mark 2 and Mark 3 have more clearance between the threads of the bolts and nuts. Therefore, you should be fine even without PTFE grease.

However, if you still want to use grease, here is my recomendation:

Finish Line Fett Synthetik Casual Grease

This grease is also very useful for other mechanical components.

Bearing assembly

Print one single wheel/tire first! Then check, if you can press in the bearing. Bearings and wheels will always come with variances. What works for me, might not necessarily work for you. If you have a hard time to press fit the bearing (I mean a really, really hard time - I took the back of my screwdriver to press them in) into the tire, scale the tire up by a tiny amount (something of 0.01%) and try again.
I've printed the tires with 0.1 mm layer height for best results!

The wheels are modeled with a small clearance. Therefore it is not always easy to press the 608 bearings into them. But here is how you will succeed:

  1. The wheel has a wider side. This side is oriented towards the holder's arm. Lay the wheel with the larger side flat on a table.

  2. Place the bearing on the wheel. Try to push the bearing slightly into the wheel. It is enough if the bearing just barely sticks.

  3. Flip the wheel with the bearing around and press with your hand hard on the wheel's wider side. The bearing should pop in and be level with the wheel"s narrower side.

  4. Place the pressing-helper tool onto the bearing and flip the wheel again, so that the pressing helper rests on the table. Now you can push again hard onto the wheel, and the bearing should pop completely into the wheel.

The pressing helper tool has a smaller diameter than the wheel"s inside diameter and should, therefore, be easy to remove.

Asymmetric Wheels

Starting with the Mark2 the wheels become symmetrical. However, there is still an entrance side for the bearings, but it should not affect functionality if you put the wheels in reverse onto the axis.

Be aware that the wheels are asymmetrical. They have a wider side regarding diameter. This larger side should be oriented towards the arms.

How I Designed This

Fusion 360

This spool holder was designed in Autodesk Fusion 360 and optimised to be printed on an Original Prusa i3 MK2s - because that is what I have. :-)

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Hmm. I'm printing everything in PLA on a Prusa i3 MK3. However, I find that all the parts are too tight. For instance, the bolts are having hard time fitting into the holes on the arms. It is so tight a fit that I have to use a hammer or pliers to get it in flushed.

Similarly, the nuts have a hard time threading onto the bolts and is extremely tight, even with grease. I feel like the bolts might have to be printed at 98% or so in order to get everything on!

You are most probably printing with a slightly over-extrusion, meaning, that your settings are laying down too much material. If you slice with slic3r, just go to your filament settings and lower the extrusion multiplier to 0.99 or 0.98.

The parts should be a tight fit, but you should not have to use a hammer! :-)

Every filament needs some tuning. You can also try to print the outer perimeter for the arms first, which will define the geometry better. However, don't use this setting for the bolts or you will print on air. :-D

Hope that this will help you get the spool holder printed correctly. If you achieve a good fit for this project, you know that you found the perfect settings for further prints also.

Happy printing,

Thanks for trying to help! I don't think I am over-extruding. The finished part does not look "messy" and there does not appera to be excess plastic on the other layers. I am printing in the basement which is cooler (the room is about 18-19 C). The bed ist at 60C and the extruder is at 210C. It may be that the ambient air is too cool, leading to some warping with PLA?

Actually, over-extruding does not necessarily result in messy prints nor does it has to be visible at all. It merely means that your print is a little bit bulkier at its perimeters which in turn is contra productive regarding mechanical fit.

As long as your print is not coming loose from the print bed you should be fine regarding wrapping. However, some PLA filaments tend to shrink after cooling. Maybe this is the primary reason?

It's possible. But wouldn't all parts shrink by a similar amount? In which case they would still be proportional and still fit together ... I'll try printing a dimensional calibration test and see whether I am over-extruding.

Hey, I just wanted to thank you for this great model. I'm using it right now on my MK3, and together with a filament guide, it is perfection. I printed mine in PETG with TPU wheels, which is a great combo. Cheers!

Great spool holder.
How do I get the STL files for the screw and nut to connect two spool holders together as in the movie?

Oh gosh, I think I will have to update the assembly video soon because the current one is much outdated.

So I have to apologize, but the new versions don't have this kind of screw anymore because it was an unrequested and rarely used feature. However, there is a center hole in the arm. Maybe I will provide a new bolting-option in the future if enough people ask for it. You are always welcome to enhance my designs with your ideas by creating remixes. :-)

Best wishes,

The honeycombed arms look great. The nuts can also be printed without top and bottom layers to create the honeycombed look shown in the photo.

However, the screws have a design problem when printed without top and bottom layers: The base of the cylinder of of the screw (the tube part with the threads) sits on top of the honeycomb of the flat screw head. It's unlike the nut, in which the cylinder of the nut goes through the honeycomb, so it's strong.

You can see both of these in the first photo on the main design page: Zoom into the nut to see the ring of the nut's cylinder around the inserted screw; zoom into the screw head on the right to see that the whole head is honeycombed. There's no screw cylinder in the honeycomb.

Because the cylinder of the screw sits on top of the screw's head, the only contact between them is the few touchpoints of the honeycomb and the cylinder edges. The fix is simple: the screw design should be tweaked so that the screw cylinder goes all the way through the head.

Also, the nut has quite a bit of honeycomb, so it seems strong. The screw head has only a few mm of honeycomb, so even with the first problem solved it would seem weak. The solution here would would be redesign the screw and arm so that the screw head was much thicker.

After discovering the above, I printed the screws and nuts 100% infilled. I think they look great with the honeycombed arms, providing a nice contrast.

I'm not even sure if I want a frame mounted spool holder yet. But I sure as hell love that honeycomb idea without top/bottom layers!

Just curious if everyone has needed glue to get the arms to print properly. I had 3 pull up until i finally gave in and put glue down. Seems to be holding.

This thing was designed to prevent warping/lifting. https://www.thingiverse.com/thing:2742479

Original Prusa i3 MK2/MK2S/MK3 Extruder Fan Covers

The thing is that you need to have the heated bed at high temperatures (for PET I use 90°C) and no unintended airflow like from open windows around the print area. The arms have quite a large print area. This is especially problematic if you print with full top and bottom infills. The forces appearing during the uneven cooldown of the print object will rip the object from your print bed.

I use no glue at all, but I use a brim of one layer in hight around my objects to prevent warping. I also clean my bed with 99% alcohol from time to time.

I'm using PLA (Hatchbox) at 65 for first layer, 60 rest. I am only printing the Left arm right now as I had a ton of issues with it pulling up. Finally gave up and used glue and it made it hold. No open windows. This is my first printer (Prusa I3 MK2S). What is the problem around "full top and bottom" infills? Where would I go to change that, and what do you suggest? Was the around the comments you made about using the honeycomb and leaving it open for looks? FYI, using Prusa's version of SLIC3R.

I haven't printed with PLA for a while now because in my opinion PETG the perfect balance between the excellent properties of PLA and ABS with just a few to none of their drawbacks. Just my opinion!

However, remembering from years of PLA usage it is not a good idea to alter the bed temperature during the print, especially not downwards as cooler temperatures decrease bed adhesion. Furthermore, other changes may also occur like variances in the nozzle-to-bed distance. Therefore, leave it at 65°C if you started with this temperature.

Regarding the top and bottom infill: These settings, which can be found at the "print setting" tab at the "Layer and perimeters" menu of Slic3r, are used to make a "solid" object with a top and a bottom cap. Without these settings, you wouldn't have a cap at the bottom and the top part of, e.g., a dice (just for illustration). However, printing solid layers with a lot of side-by-side lines results also in a lot of material that contracts during cooling. One way to minimize these occurring forces is to use an "irregular" pattern like a Hilbert curve for the outermost layers. This pattern also looks very cool.
The other way is to disable these layers (set the settings to zero) so that the internal infill is printed from beginning to end. Especially the honeycomb pattern is very forgiving because it consists of short straight lines which alter their print direction frequently.
However, not only the infill is producing warping forces on the object but also the outlining perimeters. Long lines of multiple parallel aligned perimeter segments are acting like rubber bands over the entire height of the object. Therefore, I use the brim settings at the "Skirt and brim" menu. Set it somewhere between 2 mm and 4 mm. A brim provides more area for bed adhesion which counteracts the warping forces. It is like having more perimeters on the first layer but without the rubber band effect that occurs over the entire height of the object.

If you need more information, please ask.

Btw.: Beta 5 is live...

Happy printing.

Thanks for all the great info. The left arm just finished, and is almost perfect, but I actually got some slight delamination of a couple layers in the middle (googling, might be a temperature issue?). I did print this with Honeycomb but left the bottom/top layers as default. What do you set for speed? Could this be printing too fast?

As you have the MK2S and you are using Slic3r Prusa Edition, the default speed setting should be almost perfect.

However: Please make sure you have the latest firmware and the most recent Slic3r version installed (as both depend in some setting on each other).

Firmware: https://github.com/prusa3d/Prusa-Firmware/releases
Slic3r's latest releases: https://github.com/prusa3d/Slic3r/releases

The firmware update tool can be found within the official driver package from Prusa for your OS: https://www.prusa3d.com/drivers/

Funny enough, Prusa released a new driver package on Dec. 30th with an even newer Slic3r version than the one found on the official release page. This is sometimes the case if releases of both Slic3r and the driver package are close to each other.

With the recent Slic3r releases Prusa changes the path to the configs to provide more optimized new profiles. After installing Slic3r, you will get a Wizzard dialog asking for your printer. After this dialog, you will find a completely fresh profile drop-down menu. I found that these new settings are even better and use the Linear Advance printing method, which reduces print times and provide cleaner full infills.

Happy printing

Yep, just downloaded them all before I started this print. You have any idea why i would be getting small occasional separation? I am using 220 for the PLA print temp, which seems to be the "max" for PLA. Could my room temp be causing the need to be higher? Anything about fan settings?

I am going to try the brim and not use glue. I am printing the left arm to get used to all this and learn. This is my first printer, only been using it for about a week. Thanks again for all your help, it's nice to have a great community out here!!!

You're welcome! We all had started printing at some point in our life and had to learn a lot. Now, printing is more of an intuition thing than of hard fact science. After learning the basics and printing lots and lots of stuff you can configure any slicer application and calibrate any printer (FDM printers in this case) out there in the wild.

There is no rule for "max" temperature for PLA as long as it does not smell like burned candy and the filament is not turning brown or black. :-)
Could you please provide some pictures illustrating your issue? It could be the filament extrusion multiplier (under extrusion), the temperature (bad layer bonding), variances in the nozzle-to-bed/object distance (do you have your bed temp constant over the entire print?), bad filament (you will have to test out a lot of brands and filament colors to find your perfect combination) or or or... ^^

Here is the PIC. I don't think its the PLA. Let me know what you think. The separation is light, and appears almost all on the one end with the open connector for the Z axis bar. That is also where I was getting lifting originally before the glue.

I set Brim to 3 but didn't change any skirt settings, is that correct?

UPDATE: I printed with the skirt, worked great. Is there a trick to getting the brim off without damaging first layer? Also, got a little separation mid layer, increasing temp to 225 . . .

I drew up the arm in Fusion 360 with the correct dimensions. I've printed on my MK3 and tested the clearance.

Also since the MK2 and MK3 share the same frame this arm should work for both printers. However I don't have the MK2 so I can't test that.

*** I only created one side as you can just mirror the part in the slicer to get the other side.

Beta 4 is live...

I printed a couple of each of the beta 4 arms you posted. The clearance seems to be working very well now!

I do have a question for you. In the main section of this thing, you mention that you added clearance for the axes to pass through the arms. This is probably an issue with my printer, but my axles are very tight passing through the arms. So tight in fact, that I have to use a vice to press them in. In a couple of occasions, the fit is so tight that the arms actually broke under the stress of me pressing the axles in.

In my mark 1 holders, the axles passed through the arms very easily.

I haven't tried your arms yet. But I did download your STL file and sliced a pair so they are ready to print. I just haven't done it yet. But I think I am going to fire up the MK2 printer and print a set. I can then confirm that your arms will work on both the MK2 and MK3 printers. Although I think this is pretty much moot as Martins beta 4 arms fit on both printers already. So I am pretty sure yours will as well.

Thanks for all the help guys,

The fit for the bolts is tighter than it was with the Mark 1. However, you should be able to press them in by laying them flat on a table and pushing with medium force against the arm. If you need a vice, you are probably over-extruding. Set the extrusion multiplier at the filament settings (given you are using Slic3r) a bit lower. Maybe from 1.0 to 0.98 - may vary from filament to filament depending on manufacturing tolerances.

Regarding the general fit of the arms for the MK2 and MK3, I am a little bit surprised! I made specific and significant dimensional changes, which should prevent the Mark3 version from fitting even severely on the MK2.

As I am not at home until January 2nd I cannot try it out myself.

Happy printing and see you next year! ;-)

The dimensions of the frames on the Mark 2 and Mark 3 printers are the same. There is no reason the arms should not fit properly on either printer. The only issue with the Mark 1 and 2 arms is the clearance between the frame and the print carriage was reduced because Prusa added parts to the carriage that were not there before.

So the only change you should have needed to make was to reduce how far the lip dropped down from the top of the frame and where the tires sat as the new lower position also hit the carriage when it was at the top of the Z range. Your beta 4 version seems to have fixed all that.

I see no reason why the beta 4 version could not be used on either a Mark 2 or Mark 3 Prusa printer.

So, enjoy your time away (I am assuming you are on vacation or something similar). There is no need to worry about this. I think you have succeeded.


P.S.: If the bolts are too hard to mount for even more people, I will add some more clearance to the arm! No problem!

Hello Martin!
Today i printed MK3 version, too and i can confirm that bolts are somewhat too tight in my case also. I had to file holes a bit otherwise i would break arms when assembling. If you have a chance it would be nice if you could make holes a bit bigger.
Otherwise it's a great job!

And...regarding MK2 - MK3 frame - in my case they are the same - both are 6.2mm thick (at the moment i have both MK2s and MK3 at home, will sell MK2 soon). It's only that when printing at Z height limit it's less space in MK3, so if using old (MK2) holder head will bump into it.

Beta 5 is live...

Thank you for the feedback.

Indeed I got a few requests now, and I checked the original cause of this issue. It seems that I lost a clearance setting during one of the adjustments I made. The next beta will be up in a few moments...


Thanks for the file and your efforts!

It seems that the MK3‘s frame has changed significantly over the MK2 version. It is made from thicker material, the top rim isn’t that wide anymore and because of the new base construction the entire bottom area is different (which is not important for this holder whatsoever).

So it is indeed necessary to have two arm versions within this project.

However, I think one more iteration and we are there!

I will also look into your stl for sure.


There is a Beta 3 available now. Please print it with "work in progress" in mind and report back if any issues occur.

Big thanks to all of you for the support!

I just tried out beta 3. You are so very close now. But not quite there yet.

Take a look at the marked up version of your drawing that iszio posted. The top lip that comes over the top of the frame is labeled with 5.5mm maximum thickness. I think that needs to be the target distance. I know iszio stated that the filament connector is 11mm away from the frame. But the dimension you made (about 10mm) is still too thick as it does interfere with that connector.

I have attached two pictures. One is the beta_3 version contacting the filament sensor connector. The other one is the Prusa spool holder clearing the connector.

I hope these help.


Beta 4 is live...

Cool... thank you so much!

I will do the changes asap. But we have 0:02 am right now, so I think this will have to wait until later that day! :-D

Happy printing!

Hi Martin,

Here are some more measurements to illustrate the needed clearance for the new filament detection sensor connector.

When the carriage is at the top the sensor connector is 11mm above the frame. Also the depth of the top lip is 5.5mm (max) from the face of the frame.

I've marked up your drawing with the measurements.

Please be informed that I released a beta 3.

Hey Martin,

Here is the .stl of the MK3 spool holder.

Hi Martin,

Just downloaded the MK3 left and right arm and thought I would share my observations.

1.) The frame measures 40.25mm and the gap on the arms are over 47mm.

2.) The top lip hangs about 1mm lower than the new stock spool holder.

Photos added.

Hi there,

I adjusted the design to meet the details I know so far. I also looked into the original spool holder and took measurements from there.
The current Mark 3 Beta2 is also easier to print (at the same level as the Mark 2) because I removed the enforcement of the Beta 1. This change allows printing the arm on its entirely flat side facing the bed without any support structures.

In my opinion, the enforcement is not necessary anymore because the bracket that holds to the frame is smaller now. Furthermore, I added more material to the upper lip by incorporating the "hex-style" into it. The position of the wheels moved further up in relation to the extruder carriage, which should help to print on higher Z positions as the filament should now be able to run easier across the X-axis.

Please try this design and report back, thanks!

Happy printing,

Hey Martin,

After look more closely at your dimensional drawing of your original arms. I'm pretty sure that the MK2 and the MK3 share the same frame so I think your original arms would be just fine with the shortened top lip of your latest MK3 arms (which is dead even with the new spool holder that comes with the MK3).

Once complete, if I'm not mistaken the new arms should work for both the MK3 and MK2.

Hope that helps.

Hi Martin,

I've printed your new arm and it looks like you nailed both of the issues I mentioned, plus the other changes you made are great.

However I neglected to measure the frame's thickness which is 6.5mm. It looks like your arm is set for about a 4mm thick frame.

I'm adding 2 pics to illustrate.

Right, I will adjust that as well later today (it is 9:40 am here in Germany


thanks for the information.

So the frame’s upper rim is smaller in the MK3?

The lip on the original spool holder is only 4mm? Just asking for confirmation.

Will do the changes ASAP!
Thanks again for the help.

Happy printing,

I finally got my mark 3 prints off the printer also. I agree with Iszio's observations. However, I don't think the extra 1mm on the top lip is going to be an issue.

Also, the frame is the same size on the MK3 printer as it is on the MK2. But the opening on the mark 3 spool holder arm is measuring 47mm. This is the same dimension you have marked as 40.00mm on your drawing in the details page. This does cause the lower lip to hang down below the bottom of the upper frame. I can confirm this will interfere with the cable harness coming out of the back of the carriage: but just barely. I think if you make this dimension the same size as what it was on the mark 1 version, it will be good. This may also be the same as on mark 2 version. But I can't confirm that as I haven't printed a mark 2 yet. But I will shortly.

I have added some pictures. The file, "mark3_hangdown" shows how the mark 3 arm hangs well below the frame.

The other two files show how the new carriage pieces interfere with the holder. I am afraid you might need to go back to the height you were using in the mark 1 version, or at least somewhere in between. Raising the spool axles will raise the parts that interfere away from the carriage and provide clearance.

I hope all this makes sense.


Please be informed that I released a beta 3.

I just noticed that the file, prusa3, did not get posted.Here it is.


Hi Joe,

please be informed that I uploaded a Mark3-beta arm to this project.
May I ask you to print and try the new version out and provide me feedback, please?

Happy printing,

I will be happy to try the new design out. I havestarted using PETG since I last printed this. I will print it in that.

I will be sure to let you know how it works.

Thanks again for doing this,

Hi Joe,

thanks for the pictures. I will try to find some time tomorrow (Friday) to make the changes.
However, I'll have to make some bigger design changes, but I also think that the strength will not be compromised.

Hope to provide you guys the Mark 3 beta arm still before Christmas... as a small gift... :-D

Best wishes,

I appreciate your desire to make these changes. I really like your spool holder and I would really like to be able to use it on the MK3. So far it works fine as I haven't tried to print anything close to the max Z limit. But I assume I will eventually. But please know that there is no hurry from me on this.

One thing I noticed is that the filament guide linked in a post below as thing 2219659 has a short lip that extends over the front of the frame. I have printed a couple of these and confirmed they do not interfere with the carriage at max Z height. So, if you can use that measurement as a guide for your new revision, I think that will work well.

Thanks again,

Here are some pictures. I hope you can see what I am talking about. I had trouble getting clear pictures up close.
In this first picture (prusa1), I have the spool holder I printed in blue and the top of the carriage in black.

The picture, prusa1_zoomed, is the same but zoomed in. I am hoping you can see that the top of the carriage is hitting the portion of the spool holder that locks the holder in place on the top of the frame.

The picture, prusa2, is showing the carriage in the same position. But it is next to the new spool holder that came with the printer. The prusa spool holder is also in black.Hopefully you can see that the part that extends down form the top is much shorter than yours. This allows it to clear the top of the carriage when the Z axis is at or near its upper limit. This is the only time this is an issue: when the Z axis is at or near its upper limit. Also note that Prusa increased the Z axis limit on the MK3 from 200mm to 210mm. It also added a back cover on the carriage that was not present in the earlier models.

Finally, the picture, prusa3, shows your spool holder and the new Prusa spool holder next to each other on the top of the frame. I think you can clearly see the difference. I measured the Prusa holder to extend only 6mm down from the top of the frame. This allows it to clear the carrier even when the Z axis is at its max.

I think if you reduce the length of this same piece on your arms, it will also allow the carriage to clear. I just don't know if that will make the part too weak to handle a 1kg spool.

I hope these pics are clear. If not, please let me know. Thanks for your help,

Sorry I haven't posted here before now. I originally printed a set of these about a year ago when I first got my Prusa MK2.
I loved it so much, I printed a second set for my MK2S when it came in.

So, now I just received my Prusa MK3. After I got it built, I happened to notice that the back of the printhead has a new cover that the other versions did not. Unfortunately this interferes with the spool holder you have. When the Z axis is at the top, there is less clearance between the carriage and the horizontal part of the frame. This causes the carriage to hit the part of the spool holder that comes over the top of the frame and runs down the front. (I can post pictures if necessary).

I think there may be an easy fix. The printer also came with a new style of spool holder (still not as good as yours but better than before). This has the part that extends down over the front of the frame shortened to about 6mm. I think if you shortened yours as well, it might work. But I don't know if you would be sacrificing strength or not.

I was thinking of just cutting mine down to 6mm and trying it. But I haven't done that yet. The other option was for me to try to design the side piece myself. But I also thought it would be easier if you did it. :)

Anyhow, just an FYI.
Thanks for the design, I have used the crap out of it.

Hi Joe,

thank you so much for the feedback!

Please send me some pictures of the situation where the extruder hits the part. I will adjust the arms and upload them as “MK3 Beta” for you guys to test them. Unfortunately, I have no plans for getting an MK3, so I rely on you guys (and girls) to provide me feedback! :-)

Best wishes,

I'm having issues where the filament gets stuck behind a wheel. Anyway to prevent that?

Prusa i3 Filament Guide Clip

Sorry, I missed your comment somehow!

The filament guide is an excellent way to go. However, some spool manufacturers wind up their spools too tight and too full. When the tension is released during usage, the ways of the filament thread are many! ;-)

If you encounter still issues (which mostly occur on full spools), you can always try filament from another manufacturer the next time. I found my favorite here in Germany being PETG from filamentworld.de.
Other spools caused this issue, too.

Happy printing,

OK, this is a bit radical ... but ... have you considered placing the brackets on the inside of the spool? i.e. swapping the left and the right components, making the whole assembly much narrower. Some spools might be a problem - extremely narrow spools, or extremely small spools. A modification of the shape of the arms would allow extremely small spools to be accommodated. For extremely narrow spools - you could have a single arm for both rollers?

OK, just ideas. And I may be taking the idea to extremes ... but Benchy has created an entire product line - almost an industry - around one cute little design ... why not Prusa spool holders?

Silly idea. If you flip around the arms, they are just as wide, because of the Nut components. The Arm components are just as wide as the Nut components, so there is no savings in width.
"Never Mind"

One question / concern about the "open honeycomb" printing approach (done by having no top / bottom solid layers on the arm components). It looks cool ... but ... does it compromise strength?

I guess you would need to do side-by-side destructive testing, but failing that ... don't the solid layers on the side provide substantial rigidity in exactly the direction that is needed? Yes, honeycomb is string, but I'm thinking that the failure mode scenario where the arm "folds up" would be significantly reduced if the honeycomb was bound to solid layers on both sides.

At our Maker's club (Fairfield County) we have some large and fairly heavy filament spools ... the real reason I'm printing these, because the stock spool supports are completely unsuitable ...

The honeycomb look is a style choice, not a design necessity! When you need more strength, print it that way. You can use 100% grid infill for all parts if you wish. ;-)

But, I printed lots of these holders for my friends and me with 20% honeycomb infill and not outer layers (in PETG), and none of the arms ever broke or bent.

Furthermore, you have to consider the right spool holder for your spools. You don't want to place a 2kg spool on top of your Z-frame of an i3 machine. The mechanical stress applied is no good for a happy long printer's life!
This holder is designed with average spool sized with a weight of 750g to 1000g in mind.

Happy printing,

Very very nicely designed! (although I have not assembled completely yet ... still re-printing one component, described below).

Some things that caught me off-guard:

  • Countersinking. That's what I'm calling the need to press the roller-skate bearing into the "tire" (aka "wheel") component. If you just set the roller-skate bearing so that it is flush with the tire component, the tire will not sit properly in the finished assembly. I used a U.S. Nickel coin to accomplish this - the size of the nickel is perfect, and it presses the bearing into the tire component. It might not press it as far as intended, but it seemed sufficient. However, the nickel does not have a centering pin, so some futzing is needed. Make sure that, at the end of countersinking, the Nickel coin itself is flush with the tire component. The nickel coin should fall out easily.

  • PressingHelper component. I did not print this initially, since it did not appear to be part of the Mark2 design. This would be useful, since it has a centering pin and has the intended height for the designed countersinking operation. Am printing that component now.

  • Screw component strength. The screw component (would "bolt" be a more appropriate name?) breaks quite easily. The head of all of my screw components cleaved off right at the transition from the head to the shaft, when printed with 30% infill at 0.15mm layer height. Sigh. Reprinting all the screw components now at 100% infill.

Will post pics when further along ...

Thanks for this design!!!

Hi there,

you are completely right: It should be more clear that the pressing helper is also part of the Mark 2 design.
Therefore, I have now deleted the old version but left the helper.

Regarding the bolt (this may be the more precise wording, however, I am not a native English speaker so thank you for this hint) I will add the suggestion to use 100% infill. However, I have used less infill but printed a little hotter to support layer bonding. If you break your first bolt then you know, that you don't need to tighten the nuts that much. :-D

Happy printing,

Thanks for the info!

Yes, it is easy to over-tighten. One guide I found is that when the end of the bolt exactly lines up with the Nut component, that's perfect. I guess you designed it that way ...

It turns out that the U.S. Nickel coin is much significantly thinner than the Pressing Helper component. Mounting the Tire component (might "roller" be a good name?) so that the open side of the Tire component faces the Nut component (i.e. the side you inserted the skateboard bearing faces the Nut), then the whole Tire sits closer to the arms and the whole spool holder takes up less "X" distance on the top of the Z-frame. This makes it slightly easier to pack 2 (or more?) spool holders on top of the Z-frame.

However, as you point out, weight is an issue. While having multiple Spool Holders on top of the Z-frame might be useful, having multiple filament spools continuously mounted might cause mechanical stress (and maybe later psychological stress) - not such a good idea .

Some pics included. I'm printing in PLA - just installed the rollers!

Cool, looks very neat!

If you like, please consider uploading the pictures as "Mades" by clicking on the "I Made One" button next to the project's pictures.
This will help to keep this project visible to others.

You can flip the direction of the tires if you wish, this should not affect the functionality. However, judging from experience, there is not enough room on the Z-frame to place more than two spool holders next to each other, if you are using averaged sides spools. You want to have some room left for eventually increasing the distance of the arms for broader spools.


Which files do I need to print and how many of each part? Wish that was clear.


sorry for the late response, I was quite busy lately.

I've updated the printing information and deleted the old version to make things more clear.

You'll have to print the following files in the following quantities:

1x Mark2_SpoolHolder_HexStyle_ArmRight.stl
1x Mark2_SpoolHolder_HexStyle_ArmLeft.stl
4x Mark2_AxisScrew.stl
4x Mark2_AxisSpacer.stl
4x Mark2_AxisNut.stl
4x Mark2_SpoolHolder_HexStyle_Tire.stl

Happy printing!

Wich material you recomend to make this spool holder? AbS or PLA?

I personally use PETG. It has a lot of the benefits of both ABS and PLA. However, I would go for PLA if I had to choose only between ABS and PLA. But that is just my personal opinion, as I am no fan of ABS at all.

I completely agree. ABS has a tiny advantage when temperature resistance is important. Any other application should work flawlessly with PETG, it is way easier to print.
The spool holder works perfecty in PLA, although mine one is PETG.

I just created a frame that allows you to use this amazing spool holder on top of an enclosure. It's a bit clunky, but it works.

Spool Holder Support for Enclosure
by mickoz

Works very well and looks very stylish. By chance I happened to have an old broken skateboard with only front wheels laying around. Took about 7 hours to print but it's worth it!


Beautiful and clever design that works extremely well. Thank you!

You’re welcome!

Exactly what I was looking for, works great!!!!

Happy to hear that!

I have been using this spool holder for six months now and it is great. One interesting thing I have come across is that the rollers, when printed in PLA, are harder than the rims of the spools, which are typically made from ABS. As a result, there is some wear of the spool rim in the form of black dust and fine threads that accumulates on the rollers. Once some fell off into my print. I plan to try sanding the surface of the rollers to remove the print layer lines, which I think will make them less abrasive.


Hi, I printed out the part that the bearing goes into, how tight should the bearing be? I put the 608 bearing into the first one that I printed, it did go in but was decently hard to get into it (I had to bang it a few times to get it in there, but not too hard). I then printed the part again, 1% larger and It now fits in easier but is not a super tight fit. I am unfamiliar with how bearings should fit, so before I print off the other 7 would be great to know which one I should go with. Thanks!


The fit differs from printer to printer, from material to material, and from bearing to bearing. Scale the wheels as needed but do this for all wheels or the spool will not rest evenly. The bearings should not fall off easily. Therefore, if you need a little bit of force to push the bearings in and out of the wheel it should be sufficient. But you should certainly not need super hero powers for this. These are the only advices I can provide, the rest is just trial and error.

Happy printing,

Why can I not find the parts that are in your main pic showing the honeycomb design on the outside of the parts? I tried looking through the remixes and your thing files with no luck!


There’s no such a thing like a honeycomb design. If you want to achieve that look seen on my pictures simply set top and bottom solid layers to zero and choose honeycomb as infill pattern. That’s all. Hope that helps you.

Happy printing!

For the MK2 version, you definitely want to go more that 10% infill for the screws. I've had two already break on me even with the grease.

You can also try to print with higher temperatures to ensure better layer bonding. Or you do both. :-) Different materials from different manufacturers cause different print properties...

I really like this design and it fits perfectly with the mk2s. I have printed i and it works really good, well too good actually. It rolls to easily with the bearings that i use, so that the filament starts to unwind as the print progresses. Anyone else has this problem? If so, what did you do to increase the friction on the wheels?

Did you try to use some poorer bearings?
Maybe you used some from the fidget spinner ;) They roll too fast!

love it! everything fit perfectly. beyond what I thought the tolerance capable of the printer. Bravo.

I'm not sure if im the only one having this problem, but as i have used it, they have started to bow inwards from spool weight................

Congratulations on the design, I loved it

in my opinion, it's the perfect spool design. why fuss with something going through the darn spool of filament? and why fuss with something that doesn't work with different filament spool sizes or openings? this is the best... just set your spool on top. Wide spool? just adjust one half. Ready to change the spool? Just life it up... nothing else todo.

Great design. Thanks for sharing.

Thank you for your kind words! :-)

man you should send this design to prusa himself, this is amazing!

At least the guys over at the Prusa's official forum know the design. But without users demanding it, there is no chance that this design will get any attention from the Prusa Research team. It is also not the only good spool holder design out there.

But anyway, thank you very much for your appreciation! :-)

Spectacular design! I had to tip after printing it and seeing how good it is. This should be shipped as default with prusa printers!

Thank you very much for the tip! Just what I needed to buy me coffee! :-D

The original spool holder lead to damage caused by dropped spools, this thing is a work of art and while I was waiting on replacement parts all I could think about was how this was going to be the first thing I print when it's back up.. and it was, and it was glorious.

Thank you very much for your kind words! :-)

Just added 2 remixes to this. Fantastic design, man!

Fantastic remixes! Thank you!

I'm going to save someone some time. The bearings need to be pushed all the way in, he talks about that, but in regards to an old design. In fact, an old version is all over the pictures, the video, etc, and apparently a lot has changed. Once you push the bearings in all the way, you'll find that the orientation of the wheel doesn't really matter at that point, because the bearing should be more or less centered in the rotating axis.

Thanks for pointing this out. I will make and upload new pictures, as well as delete the old ones. No time to do a new video, though.

I love your design! I've studied all of the popular spool holders and yours was exactly what I was looking for.

Fantastic (and necessary) upgrade. Recently finished building my Original Prusa and was surprised at how crappy the spool holder was. This works like a champ, thanks so much. I didn't get the honeycomb, figured out in my head the probable reason and confirmed by reading the entire description and the comments. Great trick, by the way.

I originally printed the bolts and nuts on my Monoprice Mini while printing the arms and wheels on the prusa, and the nuts were so tight I snapped every bolt trying to tighten them up (I was surprised because I've printed others that have worked). Tried reprinting on the Prusa and they fit like a glove. Perfect. took me a few days to get this printer dialled in but nearly there now and I'm loving it.

Thanks again!

Love the design, Martin!

Any chance of ever seeing a 3030 extrusion version of this?!

Haha so an embarrassing question, new to 3d printing and just got my Prusa mk2. Want to print the one one the first picture, red and black. but when downloading the file, i see many different parts and i get that i can make different designs ect. but how many of what part do i need? (arms i get, and i see left and right one, but i also noticed one flat, like the third, why this? )

Never mind! :-)

For one spool holder set you need two arms. Because the axis' screws fit flush with the arm, there is a left and a right arm version.
The left and right arm correspond to the hand-sides of looking at your printer from the front.

So you have to print all "Mark2" parts for one set with the following quantities:
1x Mark2_SpoolHolder_HexStyle_ArmRight
1x Mark2_SpoolHolder_HexStyle_ArmLeft
4x Mark2_AxisScrew
4x Mark2_AxisSpacer
4x Mark2_AxisNut
4x Mark2_SpoolHolder_HexStyle_Tire

The assembly per arm is then:

1x Arm -> 2x AxisScrews
Per installed AxisScrew: 1x Spacer -> 1x Tire -> 1x Nut

The screws usually snap into the arm very tightly. This means you have to press very hard to snap them in. But occasionally and depending on your printer's calibration like material flow rate, you can get relatively slack results. Never mind then. The spacer-tire-nut combination tightens everything anyway. However, if your assembly is very, very hard (aka. impossible) to assemble, then you have to perform some more work on your printer because it is completely out of bounds then.

Hope this explanation helps.

Happy printing,

So does the " Mark2_SpoolHolder_HexStyle_Tire" still accept the bearings?

The bearings are still the same as for the first version.

Happy printing

Awesome thanks!
Just made my second try, using slic3r with some Prusa presets but hade to change all printer setting anyway, like nozzle, filament size ect.
Followed your instructions and had great results until it loosen. On my second try i managed to make it stick with some calibration and glue on the bed. But i get some strange stringing when the nozzle lifts up and moves, like a smal top that will be in the way on the next round of layer. Temp at 210 and bed at 55. Speed and fan at default, (like 60mm/s on perimeters and 80mm/s on infill, fan at 35-100% and disabel for the first 3 layers it think it says) Any tips on temp, speed or fan-speed?

Thanks again for the help!

Your "small top" is the result of over extrusion and a leaky nozzle.
You will have to reduce the material flow labeled "Extrusion multiplier" in slic3r"s Filament Settings menu.
This can become a science of its own, but you can start simply by reducing the value by about 10%. Say from 1.0 to 0.9.

If you want to go fancy, read this: https://mattshub.com/2017/04/19/extruder-calibration/

Another option is to ensure "Wipe while retraction" is enabled in the Printer Settings menu under "Extruder 1".

Regarding your bed sticking problem:
Make the bed hotter for PLA to about 60 Degree C, and the first layer's nozzle temp to 220 Degree C. All the PLA default temperature settings are always way too optimistic in my opinion.

Get yourself a bottle of pure alcohol. Not for you but to clean your print bed. Wash away any clue with water, then clean your bed from any grease with alcohol, then apply glue stick to a cold print bed. Your prints should hold excellent after that.

I have my fans also disabled for the first three layers, or else the fan would cool down the nozzle due to air turbulences that close to the bed. However, try to enable the nozzle's retraction lift from the very first layer under the "Extruder Settings / Extruder 1". Set the first layer option to zero. It helps to avoid the nozzle from knocking against perimeters that it crosses.

Hope you get your print results right soon.

Happy printing,

Looking for a 50mm by 5.5mm pls!

Will create one, as soon as I find time for this. It is on the list! ;-)

Thank's a lot, very good Work!

Greetings from Germany

Anyone use this badboy with a bowden setup that is mounted to the top frame? I'm using a Bowden setup and I have mounted the filament motor on top of the frame. What I'm curious about is if the two could co-exist. Ideally, the motor would sit between the grips and pull directly from the bottom of the roll. Looking at it, it might work, I'm going to try it. If anyone has any experience with this, please let me know.

Thanks guys.


I have a question you can change the right and left halter so he also fits a pursa i3 pro b.
Clamp height is 46.00 mm and wall thickness is 5.00 mm
The current model mass
40.00 mm and 6.40 mm

Would be really great thank you

So, here you are:


Hope that this helps. Please report back if it fits.

Happy printing!

SpoolHolder - Hex Style - Mark 2 - Arm variations for other frame sizes

I'll try to do the adjustments in the coming week.

The modified spool arms will be released on a new project to make the distinction of the printer versions more clearly.

what is minimum spool diameter ? I ask because I have some 0.5kg filaments spool and Im not sure if this holder can support this.

But i really love your design.

Thank you for your response

I have the Taulman 910 filament running on a 12,6cm spool just fine! 10 cm spools should (!) also work.

great ! Thank you for response, keep great work.

Could I please ask you to make one for 3mm frame (Prusa p3steel)? Or upload original files? Thank you!


is the frame still 40mm tall, like seen in the schematic picture in the project's description? So you need a 3mm x 40mm version?!

I forgot about that. Just measured it, it is 50mm tall so I need 3mm x 50 mm verson.

I made these arms for my Prusa 3i Mk2 yesterday & finished them this morning. This is my first practical use of my printer.
I am blown away with the accuracy of this design.
Thank you very much for the work you put in designing it.

You're welcome! Hope you have a lot of (practical) fun with your printer! ;-)

Happy printing!

Fantastic - so much easier than the stock Prusa spool holder! Printed, assembled and installed without any problems, and I'm already printing a second one. Thanks!

I'm glad to hear that! :-D

Happy printing!

Thank you for this! This works extremely well.

You're welcome! :-)

Happy printing!

Why are the ones in most of the pictures as well as the ones made by other members honeycombed and not solid? Was that an old design?

The Mark 2 is the most current version of this spool holder. As mentioned in several other comments, the "honeycombed" look results from the print settings, where the top and bottom infill is simply left disabled (set to 0). This way the inner infill pattern is visible, and it seems that most of the users have the same design taste. :-)

Happy printing,

thanks martin, sorry about asking again, I should have read further. great model. works great.

hello my friend can you add support for Anet A8???

Hi pal,

Unfortunately, I do not own an Anet A8 printer. Without testing my projects extensively on my own, I do not provide support officially. Maybe, if my budget allows for it, I will buy me an Anet printer one day. Then it will be another story.

For now, please take a look at the Remix section for this project. There are already some impressive recreations of my spool holder. Some are also for the Anet A8. Maybe you'll find something that suits your needs there.

Happy printing,

Has anyone tried to slide a thin LED bar through the 16mm hole? Seems like if you had 2 sets of these spool holders, they could do double duty as a lightbar holder. If I can't find a good fit, I'll do a remix.

Will the head hit the top if I use this dust filter or will there still be enough clearance for the maximum height? http://www.thingiverse.com/thing:2086804

Original Prusa i3 MK2 - Snap-On Filament Dust Filter

Are those barrings skateboard barrings

Yep, 608 (skater) bearings. As said in the project's description.

Happy printing,

I really love this design but I am not sure what I am doing wrong. I printed all of the mark 2 versions of everything and the axis screws don't seem to fit into the hex_style arm. I used Slic3r prusa edition and all the default settings. Any idea what I might be doing wrong? I am new to printing so i tried reading all of the other comments first and can't find anyone else having this issue. The screws start into the nut but will not screw all the way through so maybe it is a screw sizing issue?

Have you tried to screw the nut onto the bolt separately (before the bolt is inserted into the arm)? How deep does the nut screw? Can you please provide some pictures of your problem?

Please provide more input, and I will try to help you out.

How do I share pics? I am thinking maybe my fisrt layer is too squished making the holes smaller?

Google drive ok?

So just for giggles I scalled down the screws to 95% and the fit like a charm. Even made a clicking noise when snapping into place. No idea why I would have to do that but hey, it appears to have worked (Only printed one as a test, printing 3 more now).

Also, I saw in your video where you did one back to back, what did you use to bolth them back to back? Could you make a screw threaded on both sides so you could have wheels on both sides of a single arm?

If you see something I did wrong that would have caused the screws not to fit, I would still love to hear it so I can learn. Thanks again.

My video is outdated, because it shows the first version, whereas Mark 2 is the second version with all improvements the community suggested. However, you can use the screws, nuts, and spacers found in the first version to bolt two arms together.

Judging from your pictures the size reduction for a better fit makes total sense: You have an inhomogeneous layer structure i.e. the outer perimeter vary in their vertical position relatively much. Therefore, reducing the size gives your printed object more room for play and improves the fit.

This inhomogeneity can be caused by several factors.

  1. Too high print temperatures: Your perimeters need too long to cool down and flow out of position before they solidify. Reduce the print temperature by 5 Degrees Celsius and retry. Reduce the temp further until either the layer do not adhere well enough to each other anymore, or you notice other issues like skipping extruder steps. Increase the temperature again to fix these issues. Then you will get the optimal temperature for the print speeds withe the given nozzle for the used filament. Sometimes the filament is poorly made, and the prints cannot be improved any further.

  2. That crappy original spool holder: It prevents the spool to rotate on low pull forces because of the friction. The strain that is build up lowers the amount of filament the extruder stepper can force into the hot end. If the strain released because the pull force is high enough to rotate the spool, the stepper has an easier time, and more material flows onto the print. The variances are little, but enough to cause this ripples along the vertical direction of print. Therefore, print one entire holder set and try again. You should notice a more homogenous print. Maybe your fifth screw (the first one printed with the new spool holder) on 95% scale will be way too loose then. :-)

Hope that helps you, and you will have a good experience with my spool holder. If questions occur, please ask.

Until then, happy printing!

Thanks Martin, will make those adjustments and try again. Really appreciate your willingness to help out a newb.

You're welcome, pal!

Thanks also for your tip! I'll put it to good use! :-)

Did you print the spacers? A small ring between the bearing and nut.

Worked perfectly fine for me.
Didnt need any grease, bearings fit in perfectly with a bit of pressure.
Used the inner side of the nuts to press the bearings in all the way on a table.

Although the mark 2 doesnt look like the red/black one in the image.
The surface of the arms is not perforated in a honeycomb pattern, for me they had solid bottom/top layers.
Works perfectly fine though.

It seems that it might spin a bit too freely, in the way that the wire on the spool gets very loose due to the spool rotating a bit too much. Anyone come up with a sort of damper?

I liked this design from the get-go as it was clear that a lot of thought (and refinement) had gone into it. Now that it is built and in service, I am liking it even more. I've posted a "Make" with my experiences building it (for whatever that might be worth).

Anyone else have an issue with the head of the bolt not fitting into the "cutout" on the arms? I couldnt get it to press in without modifying it a little with a dremel. Also I had a really hard time with putting the thumb screw on. It didn't really thread on as easy as they make it sound... even with PTFE grease.

Have experienced that myself but I think it's just because tolerances for the bolt is extremely tight. My first layer was slightly squished so I just deburred the hole in the arm where the bolts are supposed to go into using a craft knife and it fits like a charm. :)

I assume there is something wrong with your print settings. Maybe you print too hot or over extrude filament. Slicing it with slic3r and the standard "normal" settings profile provided by Prusa Research should give you a perfectly fitting result. What kind of filament do you use?

I had same issue with screws. Last part is extremely tight, I had to use mallet to get first one in all the way and sand others. Perhaps you can adjust their size a little? I don't think it will be an issue if they are a little loose in the hole, since nut is holding them in place anyway :)
Oh and no issue with nuts, they thread very nicely! :)

You can post the conf for Infill please, Top Bottom and Outline, on Infill do you uses Full Honeycomb or fast.
Thanks again and Very very nice model, i need mod for my Prusa i3 by Sunhokey, has a little less than 4cm frame so need modify.

Top & Bottom Layer Count: 0
Outlines / Perimeter Count: 4
Pattern: (Fast) Honeycomb (not the 3D version)
Infill Percentage 20%
Layer Height: 0.2mm (on all layers)

These settings are for the arms, nuts and screws.

For the tires, I use 0.1mm (on all layers) and 16% infill density (makes an aligned pattern).

Happy printing,

Question. I printed the Mark2 files, and I noticed that the bolt can be pushed out, so that the wheel rubs against the arm. Am I missing something, is that just part of the design, or do I need a spacer?

I LOVE this design, and am really looking forward to using it, but want to make sure it's not going to bind.

Spacer is online and seems to work! Please try it out and report back. Thank you!

Took me a couple extra days to get to the print. The spacers work perfectly!

Printed everything at .2mm layer height, in Raptor PLA from MakerGeeks. Did not anneal. (Was able to use some pink Filament that I got in a grab bag that isn't good for much :) )


Terrific! Will print it out after my current print is complete and test it out! You da man!

I will release a spacer like @maansta suggested. This gets between the arm and the wheel and will lock the screw/bolt up. Sorry, for the delay. It's quite a busy time right now.

I'm bulding the MK2 version of this. What I don't understand, is why the hexstyle spacer is not supposed to be needed for MK2. It IS needed - in order to tighten the assembly with the bearing properly. Unfortunately, the MK1 spacer won't fit on the MK2 screw which has a thicker base. Could you provide one for MK2 also - almost identical except it needs a 9mm hole. Except for this issue, the precision of this build is amazing!

"Just printed the MK2 spacer for testing - it was 100% perfect! Thank you! :)"

Cool! Thank you for your feedback.

Btw: I don't know why your comment was flagged for moderation, nor can I tell where to "moderate" it. :-/

The spacer is now online: Mark2_AxisSpacer

Please try it out and give me some feedback, if it fits and suits your needs. I haven't had the opportunity to try it out myself, yet.

Just printed the MK2 spacer for testing - it was 100% perfect! Thank you! :)

Actually the spacer is not needed anymore. The screws snap into the arms tightly and the wheels rest on the lip the screws provide. But if you, for any reason, need this spacer I will add one here in a couple of hours. Should not be a big deal.

I will give you a shout as soon as they are online.

Thank you very much - that would be great! :)

I did not experience that the screws "snapped" into the arms - which makes the assembly loose. With the (optional) spacer, I'm sure the MK2 build would work fine for everybody! Thanks again! :)

Sorry, due to my Master Thesis exam yesterday, I had not found the time to fulfill my promise, yet. But I will do so today!

These look very well thought out! Kudos on the work you did.
I'm printing them now and will let you know how it turns out.

Small question. How do these perform if a spool has a part were the edge is chipped/broken off?

can't wait to hear from you when you have them in use.

Regarding your question: I simply don't now! :-D Haven't had such a spool yet. Please tell me, if you try this out, will you?

Happy printing!

Hi Martin,
Quick question, what material did you print this in?
I'm having trouble with the screws breaking at the base. (but then again, I'm still very new to this so it could be it's my PETG settings are not correctly dialled in).

Did you print these at 10% with honeycomb infill? Which slicer do you use?
Thanks for any info.


I printed my screws with PLA (the most current ones with PLA from e3d's brand Spoolworks), at 230˚ C with 20% cubic infill. Slic3r Prusa Edition is my slicer of choice. Rule of thumb is: if your prints break easily, you can increase the hot end temperature or the extrusion multiplier. The first aspect provides more time for the material to bond. The second increases the pressure with which the filament is laid down. Start with 5˚ C increments for the temperature and 0.05% for the multiplier.

Hope that helps.

Happy Printing,

Thanks for the tips Martin, appreciate it.
I managed to get the screw printed in my PETG from DAS Filament. I had to up the bed temperature by 10 degrees. I guess that was enough to have the lower layers adhere better.

I'll be sure to remember to try your advice when I run in to a similar problem.
Now testing Colorfabb XT which I want to use for the arms (no real reason as to why, just trying to learn about the different filaments)
I will let you know how it turns out :)

Oh, sorry, I misread your post. I thought that the screws are breaking apart at the point where the cylindric part meets the hexagonal plate because you said "base." You meant the print bed! Yeah, a higher bed temperature makes sense for this kind of issue! :-D

Glad you managed to print the screws now!

Happy Printing,

No no, you had it right :)
It was at that point. Now I must say I was applying quite a bit of force trying to get them off the bed.
I was also experimenting with no solid bottom layer to get that honeycomb look. Perhaps that did something.

I found it strange too that bed temp would have that great an effect relatively high in the print.

This is the first upgrade I really think is worthwhile for my almost perfect Original Prusa. I printed all in black and everything fits perfect. The bearing just fit tight as should with no tweaking in scale. I printed some small parts with the new spool holder and worked like a charm.

So I left home with a 5 hour long print running and when I came back I noted that something went wrong. I realized the filament brand I bought here in Brazil (imported God knows from where) came full almost where the filament almost escape from the border of the spool.
So one turn escaped and get trapped in the nuts and halted the filament cutting extrusion. I put the same print over again and watched carefully and another turn escaped from the spool and get trapped over again. So I get an old filament guide from my Anet A8 and improvised to keep the filament aligned in the middle of the printer frame. Put the same file to print and now went without problems. I don´t know if anybody also had this problem since the spool must be really full at the limit. Sure after some prints the spool will empty a little and this problem never will happen again.

As a suggestion, if some more users bump in this very same problem, wold be a nice touch add a filament guide integrated in the system. As curiosity, I don´t know if this could imply in problems, but the screws could be integrated in the arm in order to be just one print for this three parts?

All in all just an ingenious design and I loving it. Thank you for sharing.


That is an interesting and not pleasant issue, for sure. However, you are the first person reporting it. Sure, the filament can slip off of the borders of the spool. That happens to me also on other spool holders, but mostly due to not paying enough attention while changing the filament and letting the filament losing tension while it slips through my fingers. However, I had never observed it during print. One user reported that the entire spool came off of the holder, but he figured out that the filament was massively tangled and the extruder kept pulling it.

I encourage every user to report this kind of issues because it is the only way to improve the design to be more and more failproof. With the Mark 2, the spool sits lower in the holder, with the wheels grabbing it more from the sides. This should minimize the issue of the mentioned user a bit.

Therefore, also a big thank you for reporting your issue.

A filament guide is on its way, but currently, I have no time to finalize it. However, there are plenty of them on Thingiverse. Nevertheless, you will also encounter problems with filament guides on high extruder positions, because the curvature of the filament is beyond good then. So search for a guide that gives the filament room the flex while the extruder prints at 150 mm and above.

I have designed the spool holders in separate parts because of several reasons. The first version has symmetrical arms so that you could print and use one arm for both sides. This would not be the case with integrated screws. Second, some users have no issues printing the arms but need several trials to print the screws because of calibration and tolerances. Separating the screws from the arms makes this attempts faster to print, and you don't have to throw away so much plastic. And lastly, with the screws separated you can print them in different colors or even materials, which gives greater freedom for creativity.

However, you can combine all parts to one print with nearly every slicing program. I know, this is more work, than using a single STL file, but that is the current status. Maybe I will provide a combined version in the future. But as I said, I have currently not the spare time at hand.

Thank you for your feedback and happy printing! :-)


I printed the "MK1" version and it worked well...too well. I had the experience of the loose filament slipping outside of the spool borders. It seems to occur in particular prints where the print nozzle moves in the widest X-axis range as it will easily pull the filament from the spool on the left and right ends of the X-axis but when moving to the middle, it pushes the filament back causing a lot of loose filament slack and the loose filament can then slip outside of the spool borders, particularly on full spools where the windings are already near the spool edges.

I think if there was "some" filament tension on the spool, there would be less filament slack occurring. With the skate bearings, the spool spins TOO easily allowing for too much slack promoting the possibility of the slack filament slipping outside the spool borders.

If this is a reoccurring issue for you, try using a spool guide, like this one:


As soon as you prevent the filament from slipping from the spool's rims, slack should not be a problem anymore.

Prusa i3 Filament guide
by Shii

Bear in mind that this issue only happened because my spool was full beyond the normal. Certainly after use about 8mm (in the diameter of the filament in the spool) this will be no issue.

I found a filament guide suitable for high prints and is already installed. But now I will only be sure of the efficiency when I open a brand new spool. I will let you know.

I suspected that you would have a good reason, but those were a smoking gun.

Once again, congratulations this amazing design.

I printed the MK2 versions for my new Prusa i3 mk2 printer. I really like how these turned out! The fit is very snug with the bolts in the frame, but the nuts screw onto the bolts smoothly and with barely any effort. Very well designed! The brackets themselves fit tightly to the metal frame of my Prusa i3 mk2, with no wobble or looseness at all. It may loosen over time, as I have to move them based on different spool widths, but I doubt it will be by much. The only item that caused me some slight concern is how tight the fit is for the bearings inside the wheels. I had to use a metal punch and tap them into place with a hammer to get them in as far as intended. I'm certain that it would take the same to remove them later. But that's something that can be adjusted by sizing the part before printing, not a concern of the design itself. These were the third things I've printed after assembling my printer from the kit, so I just used all of the defaults it came with. Printed beautifully! The only thing that might be nice would be a hole to store the filament end when not using the spool, like in the first design. But that's easy enough to add with a drill bit too ;). Awesome work Martin!

Thank you very much for your fantastic feedback and the tip you've sent! I will put it to good use and am very happy that you like the holders.

As I already mentioned in the project's description, there seem to be tolerances with the bearings, and they should be scaled (or hammered! g) to fit. With the first design users reported that the wheels were too big.

Regarding the filament hole: The hole inside the screw's end of the first design was too small if you've just unloaded it from the extruder, because of the blob on the end of the filament's wire. So cutting the thread first to get the filament into the hole was a troubling step if you were in a hurry.
So I decided to scrap the idea. But: if you print the nuts with no bottom layer and a suited infill pattern, you can have very nice filament holes! :-D Just look at the Mark 2 picture. You can also set the top most layer of the screw to zero to get the same result as with the first model.

Have a nice day and happy printing!

Will this work with the anet a8?

Sorry friend, I have no idea. I do not have an anet a8 nor is this spool holder designed for it. If your printer's frame has the same dimensions as the ones provided in the technical drawings than it probably will work. Otherwise, you have to do a remix by yourself.

Happy printing.

Any advantage to upgrading to the Mk2 screws/nuts?

Additionally, I wish you'd snug up the print dimensions a bit in regards to where it clips onto the frame. Mine still fits rather sloppy.

Love the design though! Using it on both of my Prusa MK2 printers.

The MK2 screws and nuts are designed to work with the 10mm wide arm. You can try to use the old nuts if you like, but with the MK2 versions you don't need a spacer between arm and bearing anymore, and the threads are a lot better now. Print time for four screws and four nuts was about 2,5 hours for me.

Regarding the dimensions: I am not sure, why your results are that sloppy, nor do I see how sloppy it is. You will not get a totally perfect and stiff experience with an FFF 3D-printed part, that's for sure, because not every layer equals the other. Furthermore, a perfect fit would require a perfect 90-degree cornering, which is not achievable with molten plastic.

But it should not wiggle more than 10 mm at the rear end - at most. If you look at the technical drawing at the project's update section, you will notice, that the arm has now no clearance to the frame at all. More "snug" and you will have to cut-of parts. I would suggest that you tune your print setting a little bit. Maybe a wider extrusion width on the perimeters will remove your clearance between the arm and frame. The other possibility is, that you are underextruding a little bit. But I cannot judge without more information, like pictures or a video clip.

Have a nice day.

Love your design, however, the image posted with the honey-comb internal structure arms are not posted in the thing files. Is that a feature that was was removed in the final?

No. This is just a print setting you have to set inside your slicing application.

In slic3r you simply set 0 for the solid infill shells at the top and the bottom. Then slic3r will print the internal infill on all layers. In my case, I simply printed with the honeycomb infill pattern at 20% throughout the entire structure.

You can, however, choose whatever infill pattern you like most, or you print it traditionally with a solid top and bottom layer.

Hope that helps.

Comments deleted.

that's a nifty trick!

Ahh, makes sense. Thanks! I printed it in PLA, and it fits perfectly on the frame without having to reduce or increase the scale. Getting the bearings in the mail today.


Thank you very much, such an improvement to my Prusa. My TPU prints works alot better using this holder as well!

You're welcome! Happy printing!

Which hexarm is the latest revision? There's three in the files, and nothing specific as to which is the older/newer.

Seriously, Thingiverse should fix project's management tools. Anyway, the "Mark 2" files should be gone by now.

Sorry for the inconvenience. Thingiverse has some bugs in the project management console. The other to files were actually early prototype versions of the Holder's successor "Mark 2". I was about to release it but found some issues with the design and therefore never intentionally saved them here. :-P

  • Do you guys print it in PLA or ABS? Is PLA strong enough?
  • I guess it would additionally make sense to print the wheels with some kind of flex material? NinjaFlex?

Update: Printed all parts in PLA. Everything is perfect but it would be great to have the wheels in NinjaFlex.

Martin do you think you could invite me to your project for this make in Fusion? I would like to modify the fit just a little before printing to fit my Anet 8 frame width. My name is the same on Fusion; mrjoeyman. Real name Joel West

Hi Joel,

I'm really sorry, but as I also use parts of the design for my professional work, I am not allowed to open the raw project files for public use. The CC license only applies to the exported STL / polygonal files.

But as you're also using Fusion 360 it should be no problem to import the STL file and redraw the outlines of the arms into a new sketch. In fact I have also provided a picture of the technical drawing of the arms' mounting segment here. This should not take long, as the arms are really a simple design.

You can also take a look at the remix section of this project. I think I saw an Anet 8 modification being there already.

Have a nice week,

I like the idea and it helped me to print from a 2kg spool that does not fit on my current spool holder. So far so good. On the other even with an 1kg spool the construction is not very stable. Of course it works nicely when you don't touch it but I'm afraid the the spool will fall down when I touch it. I think a solution could be to make the arms a little thicker, so that the back cannot swing anymore.

I use it with 1kg spools 24/7, I switch spools for Multi-Color-Printing and two printers are "rocking" the table constantly. Never lost a spool with these holders. As soon as a spool is sitting on the wheels it is rock solid on my machines. One way to make it sturdier is to print another arm and connect two arms with a printed screw. If you are using the two spools configuration, you will get the stabilisation effect automatically.

However, If you want it thicker by itself, check out the derivate section. One other user has already made a sturdier version. You can also increase the scale on the proper axis during slicing. :-)

Happy printing.

Very nice design! I'm printing one up right now on my M2 while waiting on my Prusa to arrive -- maybe next week.

Anyway - in general, I find it very handy to have a tap-and-die set on hand if you're printing any object with standard threads. You can pick up a cheap import set since you'll probably only use them on plastic. A easy pass of the nuts and bolts in this model through the M8 x 1.25 die and tap cleaned up the threads very quickly - now they work and feel like machined parts.

I am a bit concerned with beam-mounted spool holders in general, wondering if, perhaps, the mass that high might contribute to a subtle swaying of the z-axis. I understand the frame is pretty sturdy, but... I'll probably feel better about it when I have the printer in my hands.

In the past, I've always preferred table-mounted spool holders with a reverse-bowden setup. I'll see what I can find on thingiverse before working on my own. In the meantime, I like your design and I know I'll enjoy using it. Thanks!

You're welcome! I am happy that you like it.

I like the frame mounting, because it saves me a lot of desktop space. But you're right, having as less stress on the construction as possible is always better. That's why many people are reporting to notice less printing artifacts using my design, than as they were using the original Prusa made holder. The smooth rotation and the lowered tension benefit the print quality.

I have also thought of making a table top spool holder, but due to several other circumstances I had no time to pursue this idea. Meanwhile there is a remix of my holder, that accomplishes exactly that: http://www.thingiverse.com/thing:1940365

Please share your made spool holder with us and link it as "Made" to this project. Thanks.

Happy new year and best wishes,

Desk Spool Holder

Hello Martin. Nicely done Spool Holder. I printed Spool Holder Spacers twice (4 pairs) for 1 holder and also 3 pieces braces. Spacers are on left and right sides bearings to avoid tight rotation. Braces are for strong construction due to width spool which I am using. I am testing this construction for while. Finally wil be glued to spool holder.


Thank you for your compliment.
Please report back how your print went out.

Thanks and happy new year!

This is an awesome design! Highly functional, easy to assemble but still esthetic. I love it.

The Z-artifacts in my prints disappeared since I'm using this holder! The extruder simply had to pull too hard (and unevenly) with the original design.

Right now I'm reprinting the rolls at 99% since at 100% they are a bit loose on the bearings. Will upload a make as soon as finished.

Edit: Okay, at 99% they are way too tight, I keep the loose ones...

One suggestion for your design: I think the thread on the bolt should be one millimeter (or maybe a half millimeter) longer. When screwing on the nut it's running out of thread at the end.


first off, thank you for your compliment.

3D-printing of objects here from Thingiverse is always a matter of trial and error, since no two printers do the exact same job with the exact same precision. For most people printing this holder on a Prusa i3 MK2 the 100% scaling and all parts seems to work.
Maybe your bearings are somewhat on wrong side of a production tolerance. Mine are sitting very tight, as you can see on the video. That's why I have provided the pressing helper. As I said: it is hard to make a one-fits-all object. I hope you have found the right scaling by now.

I will look into the "running out of thread" issue as soon as I get the time for this. Thank you.

Please share your made spool holder with us as linked "Made" project here on Thingiverse.

Happy new year and best wishes,

im on the way to remake this for my Wanhao i3 plus. will upload a remix when im done testing. your design is simple yet perfect. thank u =) will update with pictures later =)

Cool! I'm glad to hear that you like it. Please link your remake to my project. Happy making.

they are in the printer now if they work i´ll upload them. and of course i will post them as a remake of yours =)

Today I did my first print after installing this. There is a big difference in the quality of the print, especially close up. I think my extruder was struggling to pull the filament off the spool. A highly recommended upgrade.

Thank you very much for expressing your appreciation. :-)

Well, I mean printing anything on my beautiful Prusa MK2 is just great, however This is truly a great design and a pleasure to make and utilize and appreciate so much...Many thanks..and Great Work. I even went out and bought PIG wheels at the local skate shop..The design is worth the respect brother...:)

Thank you so much for this compliment! ;-)

I got the 8 pack of bearings from amazon.com, printed these up, and they work great! A vast improvement for filament swapping and operation overall. Thanks for the time and the great design.

You're welcome! Glad I could help. :-)

Comments deleted.

This is awesome, any chance I can convince you to share your step files? I'm working on a similar design, and much of what you've got here would work for me.

I have to think about it (and maybe clean up my Fusion project for it^^). Please contact me via mail (at) martinmajewski.net and share some information regarding your design. Maybe we can collaborate somehow. :-)

How comes these gadgets are in 3D printer parts and not accessories or even "art" ? Not one day without yet an other cable attachment, spool, switch, filament, "sensor" ... holder/guide that anyone can make in the blink of an eye with about anything. All these gimmicks clutter the REAL parts eventually bringing REAL and useful ideas ?

BTW, even ig this spool holder is one step above the usual we can find here, I think it is not wise to put such mass being jerked by the extruder on top of not very rigid frames !

Hi and thank you very much for your opinion. I really appreciate it.

Mine is, that these "gadgets" are not accessories, because they fulfil a practical task on a printer and can greatly enhance the quality or usability of a printer. They are either not art, because they follow strict mechanical or structural rules and measurements. So design follows function and therefore there is really nothing to be called "art".

I don't know if you have any experience with the Original Prusa i3 MK2, but the frame is not flimsy (anymore). I achieve very detailed, precise and reliable 3D prints even with this "mass" on top. In fact Prusa Research puts the spools on this "flimsy" frame themselves as by design. They do not restrict neither the weight of the spools the user can put on top, nor the width of them. So you can theoretically put a 4 kg spool at the original spool holder (even though i doubt that the original design will handle them mechanically). Furthermore, my holder is not very heavy at all, so it does not contribute very much to the overall weight. I personally think, that the smoother spool unwinding even decreases the stress that the extruder puts on the frame while pulling on the filament. The other advantage is, that the user can change spools without putting any force to the frame, as they inevitably do with the original design by forcing the holder's arms apart.

But that is just my humble opinion. :-)

But you are right with the category hint. As soon as I design some decorations for the printer, I will put them either in one of your suggested places.

So long, have a nice Sunday evening and a superb new week.


Thinkverse should then have categories for "spool holder" "filament guide" "fan duct" "switch holder" ...

Now, should you come with a real novel implementation like a motorized spool holder that would deliver automatically the filament to reduce the pull required by the extruder/hot end carriage, give a shout.

I will! :-)

Thank you very much for your suggestion.

Excellent design. Downloaded!

Thank you very much! :-)

Please share your printed version with us in the "Made" section.

If you encounter any problems with my design or the provided information, or if you have any improvement suggestions, please let me know.

Happy making!

Yes, for sure. Just have to get the bearings.

I made some spool reductions for original Prusa spool holder meanwhile. Check my things. :-)

That perfectly spooled filament tho

What do you mean by that?

The black filament in the photo is spooled very nicely.

Yeah, Material 4 Print makes really nicely spooled Filament... At least at the last third of the spool! ;-)