Theremin

Australian Theremin Kits - Simple kit. The completed instrument puts out a pure sine wave tone.
thereminkits.com/

PAiA Theremax - Information about theremin kit from PAiA.
www.paia.com/theremax.htm

Theremaniacs Theremin and Harmonic Percolators - Manufactures a pitch only Theremin with changeable timbre. Also presented is the Harmonic Percolator, a distortion pedal.
www.theremaniacs.com

Wavefront Technologies - Makers of both a traditional theremin and a portable model, and also a MIDI interface.
www.theremin.ws/