This thing was made with Tinkercad. Edit it online https://www.tinkercad.com/things/fUdg0xy7x4F

I made this to hookup to motherboards so I could simulate end stops and thermistors. LED s thru series resisters (470 ohms) are hooked to bed and extruder heaters outputs and 3rd for fan or lights . Variable resisters simulate thermistors.