This project's hardware and firmware are open sourced on GitHub HERE.
If you're interested in a detailed tutorial on making your own PCB mechanical keyboard, I wrote this article for Hackspace Magazine: LINK
If you'd like to purchase a keyboard kit, they are available for purchase in the Bolt Industries store HERE.
The keyboard is constructed from three layers of FR-4 PCB. The bottom layer primarily covers the sharp solder pads, the middle layer is the main PCB, and the top layer is an aesthetic trim that also provides most of the keyboard's rigidity. I chose the Raspberry Pi Pico because it's abundant and affordable. The keyboard runs BMK, my own custom firmware written in the Arduino IDE, as well as KMK, a mainstream mechanical keyboard firmware that's been around for a while. There's nothing special or unique about the key layout, however it's really easy to program macros to do copy, paste, undo, redo, etc as well as writing Unicode characters like Ω,μ, or °! I also added a built in USB hub!
Matching macro pad:
There wasn't enough GPIO pins in the Pico to add four more rows of keys for the numerical keys, so I instead made a separate numerical keypad that runs the same firmware, but with fewer keys.