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.

NppExec adds a Console window at the bottom of Notepad++'s window; This Console window allows to run different console programs directly in it; Also there is Plugins -> NppExec -> Execute... window ...