[A. Smyth] passed this along – it’s another take on the non-mechanical dance pad. The first prototype used IR detection, but apparently the hardware was flaky. The new version uses cheap laser pointer style diodes with photo detectors. Personally, I want to see one that breaks the laser into a line and collimates the resulting beam, and senses beam interference by measuring the intensity. (And it would look incredible with a fogger) The electronics are pretty simple – the photocells are interfaced with the guts of a USB game pad and breaking the beam creates a button push.