A Flexible, compact holder for a single USB drive and a variety of keys.
UPDATE Check out D-01B for a design which will accept a wider variety of keys!
Though this is primarily designed for 3 or 4 house keys, a single car key, and a Kingston DTSE9 G2 USB Drive, by omitting the middle parts (Top 2 and Base 2), it can fit any configuration of keys you wish (This removes support for the centre nut, do comment if you want an updated version with a fix).
The STL files have separate bodies which signal where a material change can be made to add a stripe around each half in a colour of your choice (I chose red). This can be ignored and printed in one material if you wish, though it doesn't look as good. I used the function in Prusa Control that allows you to add filament changes, details can be found here for other printers: https://www.prusaprinters.org/color-print/
I have also included the Key "washers" i used to improve the fit of the keys on M3 bolts, They may work for you, or if you do your own, add it as a remix!
Maximum of printer (0.05mm)
The Top and Base of design have been split to optimise print speed and quality. All parts are in their optimal print orientations, but you can rotate the USB cap if you want to minimise support material.
Top 2 and Base 2 can be omitted if you have different keys you wish to fit in the holder, though you will lack the central section which helps support the two halves, and will likely need different screw lengths.
Prototyping was done with 0.2-0.3mm layer height, but to reduce stepping use the max resolution of your printer (0.05mm looked good on a Prusa I3 MK3).
For reference, my final print settings were:
Prusa Silver PLA & 3D Prima PrimaValue Red PLA
210-215° Extruder, 55-60° Bed
Top 1 & Base 1: 0.05mm Layers, ~3 Hours each, Mixed PLA
Top 2 & Base 2: 0.1mm Layers, ~0.5 Hours each, Silver PLA
USB Cap: 0.05mm Layers, ~0.5 Hour, Red PLA
Minimal finishing should be needed, especially if you print with a minimum layer height.
If you print with a thicker layer height then some sanding would make the stepping on the angled parts look better, but will not affect function.
Assembly should start with gluing the two top parts and the two bottom parts together. I printed in PLA and used some Cyanoacrylite (Superglue) to secure them, using m3 screws to locate the parts accurately. You may need to use different adhesive for other filament materials,
The next step is securing the USB drive and putting the cap onto the top. The USB cap is intentionally a tight fit into the Top of the holder, so will take several attempts to insert. Don't worry, it will work!
After that, you will need 3 M3 countersunk screws (mine were 20mm long, but this may be different if you have more keys), and 3 Nuts (I've used Nylock nuts for extra security). Thread them through the Top and then use M3 washers between the keys to space them out a bit.
Slide on the Base and then Secure from the back with the nuts. The central nut is recessed quite a way, so you may need pliers to hold it in place while you tighten it.
There is a key ring loop on one side, to which you can add anything else you may want (I've added a lanyard to mine). It is not very thick but in testing has proved strong enough to work without breaking when the holder is full of keys.