After this tedious step, he designed a PCB that hosts an Arduino Nano to accept input, two MCP23017 GPIO expanders to give it enough outputs, and CD4066BE CMOS switches to trigger the connections.

Arduino. AVR - Arduino Uno, Mega, Leonardo, Pro Mini, Nano etc. NOTE: Arduino boards based on ATmega328 (Uno, Pro Mini, Nano etc.) and smaller are NOT recommended. This is because the ATmega328 MCU is ...