Fun-fact: the digital rotary knobs on most equipment (given name: rotary encoder) are pretty much built like this - a disc with conductive patterning read by br

Fun-fact: the digital rotary knobs on most equipment (given name: rotary encoder) are pretty much built like this - a disc with conductive patterning read by brushes (well, bent contacts). Only the far more expensive rotary encoders are optical with an etched or printed glass disc, like typically found in industrial incremental encoders. These optical encoders typically cost 10-15 EUR a pop. Btw. using keyboard controllers to poll many switches isn't actually that unusual, but definitely a nice hack.