First off, let me please ask that if you like these designs and find them useful please do like, follow and share my content. And if you have any ideas or concepts to modify the content I would love to hear!
I designed this spool holder to mount to a $2 plastic container purchased from a cheap variety store. The internal hub will be able to mount within most container shapes, though the outlet may need to be redesigned to suit (I will amend at a later date) a flat outer perimeter, as the container I purchase is taper slightly.
The centre hub is 45mm outside diameter and 75mm wide. The end cap screws in to locate the spool and stop it from wandering off the holder. The outlet has a 9.5mm hole for use with ~10mm pneumatic fittings. The one I have pictured is for 4mm ID teflon tube. I like to run a teflon tube directly to my printers extruder from the enclosed filament holder so as to protect the filament as much as possible.
In future design amendments to this I wish to add a filament clamp within the enclosure to store filament when not in use, as well as a location for some desiccant material. For now though, it works well.
All bolts are M4. I used 25mm long nylon bolts and cut them to size as I fit them.
I also use the filament spool holder in conjunction with the filament cleaner https://www.thingiverse.com/thing:2579570
If you cannot find a similar type of container to suit you could even print the entire enclosure and design a lid for it as well?!
Please do let me know if you would like any changes. I am happy to help out :)
UPDATE - 1/11/2017: Included Parts base_01, base_02 and base_03 which are a new stand that incorporates a draw and vent system. This will allow the user to add some desiccant material to the draw to help keep their filament spools dry.
Try printing the cap without support, it is possible with the correct machine and settings. Though if you do have trouble with overhangs I suggest using some support material on the cap and printing it so the thread points in the positive Z direction.