3D-Printing Parts and Slicing


If you bought the kit with the 3D-printed parts included, you can skip this part!

Download 3D Models#

The POLY555's models are hosted on Thingiverse at https://www.thingiverse.com/thing:4676728/files.

Download them and then come on back here!


There are five parts you'll need to print:

  1. Enclosure top: The enclosure's top with window, speaker grill, LED cavity, and branding engraving
  2. Enclosure bottom: The biggest piece! The PCB mounts onto this.
  3. Keys: The piano keys. This needs to be printed in two colors, see below.
  4. Mounting rail: This mounting rail piece will sit between the PCB and the keys.
  5. Volume wheel: And the volume wheel fits onto a potentiometer and is exposed on the enclosure's side.

Reduced test case#

Wondering what that sixth file called "reduced_test_case" is for?

This is optional but helpful for confirming your printer and slicer will be able to print the full POLY555 and have it assemble as expected. It takes about 30min.

If the test case's two pieces are difficult to fit together successfully after printing, revisit your slicer settings and ensure the printer is calibrated. Repeat until successful.

Slicing recommendations#

PieceLayer heightColor changePrint time
Enclosure top.2mmn/a4hr
Enclosure bottom.2mmn/a8hr 30min
Mounting rail.2mmn/a30min
Volume wheel.2mmn/a10min


  • Models assume Fused Deposition Modeling with a standard .4mm nozzle. Using a bigger nozzle will likely result in a loss of detail and possibly missing internal walls.
  • You may find the bottoms of the keys stick together because the plastic has expanded too far into the gap between them. See if your slicer has a setting called something like "Elephant foot compensation". Otherwise you'll need to carefully cut off the excess plastic with a utility knife.
  • The 3D-printed parts were designed using PLA. Other filament types like ABS are not recommended and will likely have fit or tolerance issues. (If you find that you need to drill or file your prints, that's a good sign there'll be other problems too.)
  • Any supports the models need they'll already have, they'll already be rotated to the correct orientation for printing, and they shouldn't need brims. Brims on the keys, in fact, could cause warping on removal.
  • The enclosure pieces are big and may warp off the bed plate without good adhesion. I tend to use a lot of glue on the bed and stay away from plastics that shrink. Watch the first couple layers of these while printing, especially around the text engravings -- if you see bad adhesion, stop the print to remedy the situation and start again.
  • If the prints aren't fitting together well, check to see that the corners aren't bulging. We should see clean, sharp edges on the mounting rail and the keys' mount. See if your slicer has settings for "coasting" or "linear advance."