Lasers and light guns get together to make some beautiful - or at least interesting - music.
Using electronics know-how, an old NES Zapper, and plans that he found in a magazine, a retired math teacher, known only as "duboisvb," built his very own Theremin-style musical instrument. It took a little trial and error to get the thing working, but the Zapper - or at least its shell - proved to be the thing that turned the tables.
A Theremin is an odd instrument, in that you don't actually have to touch it in order to play it. Theremin's use radio waves to detect the position of the player's hands, and then translate that position into particular sounds. Duboisvb's version operates on a similar principle, but it uses a laser rather than radio waves, and plays a range of MIDI sounds, rather than generating a tone on its own.
The device is based around a microcontroller that can connect to a computer via a MIDI jack. Duboisvb's original design used a simple laser pointer to provide the beam necessary to make the instrument work, but he found it very difficult to mount it properly. The breakthrough came when he swapped his original mounting for the NES Zapper. He hollowed out the Zapper, which despite being a "light gun," doesn't actually generate any light itself, and put the pointer in the shell. This made it much easier for him to get everything lined up right and to get the whole thing working.
It's not going to be an instrument that someone is going to compose symphonies on, but it looks like it's capable of making some really interesting music. I'd love to the see the Super Mario Bros. theme, or maybe the Legend of Zelda theme played on it; it seems rather fitting.