I just finished my writeup for my Music Synthesizer kit project. The kit was made for a soldering workshop for the Boston University Artemis Project (http://www.bu.edu/lernet/artemis/), which is a Women In Technology Summer Program for rising high school freshmen. I work for the BU EDF (edf.bu.edu), which normally makes electronics for physics experiments, but we also do outreach electronics programs.
Normally the workshop would have contained a POV light toy, but we wanted a change of pace and I took lead to develop a music synthesizer with an 8 button keyboard, which can also act as a sequencer. There is a phototransistor which can pick up a light based message generated by this page, which my coworker Sam Damask made