Single 4x4 PCB 16 Key macropadAssembled a single board version of the 4x4x4x4x4 PCB. A 1/16th thick aluminum plate was used as the bottom. This can run the same firmware as the 4x4x4x4x4 using just the 4 left most columns. I also used kbfirmware.com to create a hex using this json file.
Arduino Micro clone socketed to the bottom.