How They Roll Robot Balls--that is, computerized spheres that can be rolled in any direction by touching a smartphone--are ready to take over the world.

Entrepreneurs: Ian Bernstein, a former robot builder for RoadNarrows Robotics in Loveland, Colo., and Adam Wilson, who graduated from Northern Colorado University with math and physics degrees in May.

What possessed them: The challenge of creating a toy that, Bernstein says, had never been made before. "We can make a remote-control car in a day that we could sell that day. Really not that hard. But I've never seen a robotic ball."