http://www.instructables.com/id/The-TapeScape-Audio-Robot/

It seems to me that if you're of at least drinking age, you've got an old tape deck and a box full of old cassettes collecting dust somewhere in your house These audio artifacts of yesteryear have been eclipsed many times over, but for some reason so many of us can't seem to part with these old treasures. We decided to give them new life by creating TapeScape and the BoomBot. Now this obsolete media can be re-used and given new life instead of ending up in the garbage.

The idea was to make a robot almost entirely out of tape player parts, and mounting a tape head that continually drags itself over a flat field covered in audio tape (the TapeScape). So you're not playing a tape, you're playing on a tape. The resulting audio output is a glitchy sound experience with enormous opportunity for creative expression.