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Even if you're not familiar with the Theremin itself, it's very likely you've heard its loopy electronic tones before. Remember those spooky sound tracks from 1950s science fiction movies? Well, chances are pretty good that those oscillating noises were generated by a Theremin.

Designed by Russian physicist Leon Theremin circa 1919, the two-handed instrument was one of the first ever electronic musical instruments and the first instrument one could play without physically touching it. Thirty years after its invention, the Theremin was popularized by American synthesizer godfather Robert Moog in the 1950s and immortalized in the classic Sci-Fi flick The Day the Earth Stood Still.

A full-fledged Theremin will set you back nearly $400, but with the instructions below, you can build a pocket-sized Theremin-like instrument that wont break the bank. Unlike the real McCoy which relies on grounded variable capacitance for changing frequency and volume with the wave of a hand, our Pocket Theremin uses variations in light for producing its unearthly vibrato.