Nick Hardeman’s theremin-like music thing:

This instrument experiment is similar to a theremin. The IR sensor on the right (when the speaker is facing you) controls the note: a, b, c, d, e, f, g and is represented by the changes in color. The IR sensor on the left controls the octave of the note. The whole thing is powered by a 9V and an atmega bootloaded with arduino software.

Interesting DIY project – but it’s hard to improve on Léon Theremin’s classic theremin.