Jimi_hendrix There is such a thing:
Pocket Clanger Theremin - Of course not exactly look for, but the principle is similar ...
And what a subject, the more likely the program of course entertainment .... If done seriously, it must be Claudia landscape with 12 keys, finger-friendly, and makes it easy to transpose in octave - plus the ability to apply multiple sounds at once, and additional buttons , which could advance to hang such necessary chords, and of course built-in metronome .... dreams .... in the meantime, a toy of course, a lot stylus not play, could be used as akkomponiment guitar during drunken gatherings, but too softly plays only when connected to speakers specially !!! And this idea ....))))