15 bikini models and a bunch of conductive paint. You just need a Ningen Gakki, coming this summer from Takara Tomy. It has four conductive patches on the limbs of its vaguely anthropomorphized shape. If two people each touch one of the patches and then touch each other a circuit is created and a note is played. Up to four people can play songs or drums by clapping hands or, as you can see in the video below, generally slapping each other about. The notes don't appear to get louder the harder the hit, but perhaps that's for the best.