Compact keyboards are super cool -- I use a TKL -- but sometimes you just miss having a big, old number pad for data entry and calculations. The Numpad 4000 is just that! Plus, you can move it off to either side of your main keyboard for ideal ergonomics.
You can build the custom mechanical Number Pad of your Dreams with the Ortho NeoKey Snap-Apart PCB, a Feather RP2040, and CircuitPython. Customize the physical layout on this diode-matrixed, NeoPixel-lit wonder board!
This project should work well on nearly any CircuitPython-capable Feather board. I chose to use the very lovely Feather RP2040.
Key Switches and Keycaps
The NeoKey Ortho 5x6 PCB uses up to 30 keyswitches and key caps, although for the Numpad 4000 you'll only need 22.
To build the Numpad 4000 as designed here you'll need a set of number pad-specific keys. I used SA profile, double-shot Maxkey keycaps -- these numberpad keys happened to be left over from a TKL (ten key-less) build I did. Talk to a friend who has ordered some fancy keycaps before -- in many cases they'll have left over numpad keys as people tend to make smaller boards!
Or, go for a fully orthographic build using 1u keycaps such as these DSA profile ones:
M2.5 x 18mm Screws x3
These ones from McMaster-Carr are nice.
You'll need a 3D printer and filament to build the switch plate and case. Alternately, you can make a variant stacked design using acrylic or wood on a laser cutter or mill, or even with chipboard and a CNC cutter such as the Cricut.
You'll also need a soldering iron, solder, and thin wire such as this: