a lot of custom keyboards use a amtel avr controller which is easily flashable with custom firmware. I think I can see a teensy like board in the picture. here

a lot of custom keyboards use a amtel avr controller which is easily flashable with custom firmware. I think I can see a teensy like board in the picture. here is an (the) example in c: https://github.com/qmk/qmk_firmware https://github.com/qmk/qmk_firmware