So the project has changed! sort of. Back to closer to what it was going to be before.
It's going to be an optical theremin, but I'm going to do something crazy with it. Ideas for the something crazy right now include a clear pvc sword which changes what it sounds like when you wave it around, a really annoying mousepad, and an alarm clock that screams if you for using the snooze button. That last one might be hard because... it'd be screaming all night unless I figured out how to rig a timer up to it. I don't really know.

I like the sword idea, just because it'd be fun and I know I could probably get started on the non-electronic part at home over break, since my electronic parts haven't shown up yet.