Jeff Han demonstrated this concept a few years ago, but without the laser: http://cs.nyu.edu/~jhan/ledtouch/index.html http://cs.nyu.edu/~jhan/ledtouch/index.ht

Jeff Han demonstrated this concept a few years ago, but without the laser: http://cs.nyu.edu/~jhan/ledtouch/index.html http://cs.nyu.edu/~jhan/ledtouch/index.html I tried to wire one up myself but couldn't get it to work. I think certain LED matrixes don't work as well (maybe translucent vs transparent LEDs)