A special mini amp channel switcher/FX loop pedal (When you actually only use 1 of the 2 functions and the other is always on or off) Details in comments. : r/diypedals
DIY Channel Select Switch - YouTube
Build of a 1 channel looper switcher
DIY 2 button guitar amp footswitch for Epiphone Triggerman 60
Guitar Dreamer: DIY footswitch!
Amp channel switch. LED question
How to make: A/B Switch Guitar Pedal w/ LEDs - YouTube