Now you’re going to implement, iterate and develop a working prototype. Not much to say about this, except that each of the ‘prototype’ groups should cross-over and work on making interaction happen across groups. These fist-cut prototypes need to clearly demonstrate your concept. Not all parts of each prototype needs to be fully functional, but there needs to be a clear path to making them functional. In other words, some parts of each prototype can be “wizard-of-ozzed.”