Welcome to the world of the OPTIGAN (NOT "Optigon," "Optagon" or "Octagon!")! In the early 70's, Mattel devised this OPTIcal orGAN to play back the sounds of REAL instruments, encoded on celluloid discs like concentric rings of movie soundtrack. The result was pretty crappy sounding and soon forgotten by the world at large, but if this sounds to you like perfect fodder for an obsessive, almost fetishistic website, then you're absolutely correct!
Sean on "Mimi":
Needless to say, the Optigan—one of the eeriest and most counterintuitive instruments ever invented—was the ideal tool. Never mind the fact that it was out of tune with itself, covered in dust, and about as rhythmically accurate as a one-legged tapdancer in a roomful of mousetraps. We had a notion that an Optigan could solve our problems, so Chris found a way to make the Optigan work, eventually constructing a rhythm track so creepy and beautiful that the song itself needed only to hang across it like skin on a skeleton.