[jpindar]

I've thought of making various custom (and ruggedized) game peripherals. The electronics and switches I could do (assuming the ICs are available), but designing housings to be 3d printed might be tricky.

For a guitar, however... possibly having the body made of wood like a real electric guitar could be a selling point.

[bombcar]

I've always thought the way to go is take a normal controller say, and tear out the internal electronics, replace the switches if needed with stronger/better ones, and put it in a custom 3D printed housing.

[Kaze404]

There are plenty of guides for 3d printed guitars specifically, and from the perspective of someone who's never 3d printed anything they don't seem too complex. Not sure about other controllers though.