"I made the Digital Chocolatier, a machine that builds chocolates layer by layer, from the bottom up. Four tubes hold nuts or chocolate. The chocolate tubes are heated for melting. For each layer, a servomotor positions the correct tube, and a valve releases the contents. Chocolate's hard to work with—it clogs—and we had to fabricate the parts because existing chocolate valves are too big for home use. Printing takes about a minute, and a thermoelectric plate and heat sink cool the printed treat. This machine is the first step toward a 3-D food printer. I'm convinced it's possible to create things you couldn't do by hand—for example, a cake that's chocolate and gradually swirls into a lemon pie. That's something we can do on a computer with a digital image in 10 seconds. Wouldn't it be cool to do it physically?"