I've seen references to making spin art in a salad spinner; the housing and drive mechanism are already done for you. They were using paper plates, but I imagine you could rig up something that would let you pin or clip down the card stock or paper of your choice.

Even if you were to build your own cabinet-based unit (with a viewport, naturally!), you could make it more interactive by doing without a motor. Bevel gears... crank handle... roller clutch... now you're talking!