1. Add a cup of grain to a quarter-cup of water in a sealed container overnight in the refrigerator. This gets the grain moisture up to at least 20 percent.
2. Cut a three-quarter-inch ring slice (pictured) off a seamless-steel tub with a 2.5-inch inside diameter. File the edges smooth, and wash them. Mount the ring to the center of a flat metal plate (we elected to weld it).
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.