Gaming keypad for left handers

I finally got around to printing proper keycaps, painting the labels with acrylic paint and sanding them down. I am satisfied with the result, but there is still much room for improvement.

I sanded the caps down to 320 grit sandpaper, especially on the black keys you see, that this is not enough (see the (unsanded) black key left to the ALT key for comparison), but it already has quite a nice feel to it.

I did not print all keys yet, as I am still tweaking the keymap in some places.

The acrylic paint worked okay, although not as good as I had hoped. There are PLA particles from the sanding stuck in the paint and when drying, it contracted, so I had to paint over it multiple times and even the the results were suboptimal. Perhaps next time (if/when there is a next time, I got plenty other projects in the pipeline), I will try colored epoxy - but maybe I will go the whole step to make moulds for the caps.

I assembled the keypad and put on a range of keycaps (mostly test prints, but also some off-the-shelf keycaps my roommate had lying around).

I tested it and it worked, but sometimes key presses were not registered. First I thought it was the switches not being closed, but it turned out to be a firmware problem. I used the ergodox_ez qmk firmware for the keypad, which is configured for a split keyboard. Normally the right side is connected via USB (as it is for the keypad), but it is also connected to the left side via a 4-pole 3.5mm jack, speaking I²C. This normally works great, however, as my keypad has no left side talking back, it waited for a response, which lead to a lower sampling rate and thus key presses not being registered.
After a lot of procrastination, I finally created a [custom firmware in qmk](https://github.com/AberDerBart/qmk_firmware) which was no big deal after all and now it works like a charm.

Next step: print and paint the final keycaps

I did some experiments with painting keycaps. I painted the letters of the printed caps (which are recessed in the keys) with acrylic color (left), then sanded the cap smooth the  next day (right). The result is not perfect as there are small imperfections in the print where the paint still sticks, but its good enough for now.

I 3D-printed the case in white PLA. For now, I just used a model from Thingiverse.

As I want the two main layers both to be printed on the Keys, I need custom keycaps. So I scripted some OpenSCAD and python based on the awesome KeyV2 project to generate 3D-Models to print.