Our friends at Technology Will Save Us grabbed a jar of Bare Paint and mashed it up with their cool Lumiphone, The Lumiphone uses a pair of LEDs and Light Dependent Resistors (LDRs) to control the pitch and volume of the sound coming out of its speaker. Its a seriously addictive piece of kit. Daniel used a few strips of Bare Paint and some cans in place of the LEDs and LDRs.  Resistance is varied by rolling the cans back and forth. One can controls volume and the other controls pitch.

The Lumiphone in its natural state.

An awesome GIF of Lumiphone assembly (with a free "thumbs up" at the end).