I already learnt a lot of things about keyboards with my previous laptop project (in particular matrices) reusing a old Dell mini keyboard. But I wanted more, and those mechanical keyboards seems very nice.
So I decided to give a try. I really love STM32 microcontroller, but in the mechanical keyboard world, it seems that AVR are everywhere. So I first checked if nobody tried with STM32, and started with that. In the same time, and since Eagle changed their policies, I started learning Kicad.
The original keyboard is nice, but I only wanted one microcontroller, and decided to use a dedicated chip for led matrix (http://www.issi.com/WW/pdf/IS31FL3733.pdf). The main problem with these huge PCB is cost (sorry for this time OSHPark friends), so I ordered them on EasyEDA (5 board + shipping for $62). The switches however are available on Digikey, and ordered the caps on https://mechboards.co.uk/.
I did not have major issue soldering the board and testing it : everything were fine the first time (ok, just some resistor was to close to the switch, but it works).
Finally, I reused my other keyboard firmware and improved it to support LED.
Hardware and firmware sources : https://github.com/julbouln/stm32_mech_keyboard