An optical theremin with built-in echo. Cast shadows on it or wave around near a light source for science fiction-y sounds and washes of tonal interactions. Use a blinky bicycle light or a flashlight for interesting effects. 

Demonstration video:

Sound is activated by the silver button. Push it rhythmically for interrupted beeping textures. 

The echo time is adjustable from zero to several seconds. Runs on a 9v battery, easily accessed through the back panel. It has a 1/4" output jack for connecting to guitar effects pedals, amplifiers, etc. 

Handmade to order in Chicago, USA. Please allow 2-3 weeks for shipping.

Please get in touch with any questions, I'm happy to answer.