You may remember playing with zoetropes as a kid, or at least their flipbook equivalents that converted a series of 2D stickman images into an animated story. Such devices proved popular from the Victorian era all the way up until movies became all the rage in the 20th century. Now there's the 21st century version -- a 3-D zoetrope that creates a spiraling animated ilusion.
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.