An EV3-controlled motor powers the whole thing. He also makes use of an obscure part–the 14-tooth bevel gear, last manufactured by LEGO in 2002 ... or 16 teeth, medium-sized ones 20 or 24 ...

This Lego Mindstorms EV3 guitar creates music using 12 fret positions and 5 buttons, with sound produced by the EV3 Brick’s ...