Inventor/creator Michael Una has built a delightfully simple hand gestural electronic music instrument which acts as an optically controlled squarewave generator. He has housed it within a petri dish enclosure making a very simple compact design."This minimalist electronic musical instrument eschews esoteric interface in favor of intuitive, expressive control. One button turns the device on or off, which can produce a continuous tone or a rhythmic sequence. One sensor varies pitch of the output waveform in response to ambient light. The resulting system encourages playfulness and body movement."
Here, is a demonstration of the optical theremin synthesizer, which outputs a square wave whose pitch is variable in relation to the amount of light striking a photocell mounted within the device.
Michael hand-builds the devices and sells them for US$25, he also makes the plans freely available for anyone wishing to build their own.
Source
