Model your own plate and case in OnShape, from layout all the way to a printable STL
Difficulty
Intermediate
Time
3–5 hours
Steps
7 stages
Every file for this build is up on GitHub, the plates, the case and the firmware
Our GitHubGather everything below before you start and the whole build goes a lot smoother. The printable parts are on GitHub, so you only need to buy the hardware.
| Component | Qty | Specification |
|---|---|---|
| OnShape account | 1 free | Free at onshape.com, browser based with no install |
| 3D printer | 1 | FDM printer with 0.4mm nozzle recommended |
| PLA filament | ~100–200g | PLA is easiest for plates and cases |
| MX switch (for fit testing) | 1 | Test one switch before printing the full plate |
| Calipers | 1 | Optional but very helpful for measuring switch fit |
01
OnShape (free account, runs in your browser)
02
3D printer slicer (PrusaSlicer, Cura, or Bambu Studio)
03
Calipers (recommended)
Work through these in order. Anything you need to download along the way, the plates, the case and the firmware, is already waiting for you on GitHub.
01
Step 1 of 7
Before opening OnShape, decide your key count and grid arrangement on paper. For a grid-style macropad, note the number of rows and columns. For a staggered keyboard layout like the MonkiiBoard39, sketch the row offsets. Key spacing for MX switches is 19.05mm centre to centre, and that is the number everything else is built from.
Pro Tip
Draw your layout on graph paper first, one square per key unit. It takes 5 minutes and prevents expensive reprints.
02
Step 2 of 7
Create a free account at onshape.com and start a new document. Create a Part Studio. Set your units to millimeters in the document settings. OnShape saves automatically to the cloud so you never lose work. All MonkiiBoard files are also stored here, so you can copy our documents as a starting reference.
Pro Tip
Use the OnShape keyboard shortcuts, "L" for line, "D" for dimension, "E" for extrude. They are fast once you know them.
03
Step 3 of 7
Create a new sketch on the top plane. Draw your first switch cutout, a 14mm × 14mm square centered at the origin. This is the standard MX switch hole size. Then use the Linear Pattern tool to repeat it across your row and column count, with 19.05mm spacing in both directions. Add mounting clips if you want them, a 3.5mm × 1mm notch on each side of the cutout lets the switch clip in.
Pro Tip
Print a single-switch test piece first, just one cutout in a small square, to verify your switch fits snugly before committing to the full plate.
04
Step 4 of 7
Close the sketch and use Extrude to give the plate thickness. For a standalone switch plate, 1.5mm is the standard, and that is what locks the switches in at the correct height. For a combined plate/case top, 3–4mm gives more rigidity. Extrude downward from the sketch plane.
Pro Tip
1.5mm is the MX standard plate thickness. Going thinner makes switches loose; thicker makes them hard to remove.
05
Step 5 of 7
In the same Part Studio (or a new one), design the case shell. Start with a rectangle matching your plate footprint and extrude it to your desired height, typically 10–15mm for a low-profile feel. Shell the body using the Shell tool, leaving 2–3mm walls. Cut a rectangular opening in the back wall for the USB port, positioned to match the Pro Micro's port height.
Pro Tip
Leave at least 2mm of clearance above the Pro Micro inside the case, because components and solder joints take up more space than you expect.
06
Step 6 of 7
Add M2 screw bosses to the case interior, which are cylindrical posts with a 2.2mm hole for the screw to self-tap into PLA. Place one in each corner and one or two in the middle for larger boards. On the plate, add matching through-holes at the same positions. This is how the plate seats and locks into the case.
Pro Tip
A 2.2mm hole self-taps cleanly with an M2 screw in PLA. No heat inserts needed for a simple build.
07
Step 7 of 7
Right-click each part in the OnShape part list and export as STL. Import into your slicer. For the plate: 0.2mm layer height, 40% infill, no supports. For the case: 0.2mm layer height, 20% infill, supports only if needed for the USB cutout overhang. Print the plate flat for maximum rigidity. If you want something to compare yours against, every plate and case STL we have made is on GitHub.
Pro Tip
Slice the plate with the switch face down on the build plate, that gives the cleanest surface finish on the side that matters most.
Stuck on a step, got a tip, or just finished your build? Drop it in our form. We read every single one and it helps us make the guide better.
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