Building a line-follower that is this tiny is a different story. The surprising thing for us is that despite how it looks, this robot whose name is Rizeh doesn’t use wheels to get around.

and that has to be one of the greatest compliments to a maker. [Greg Zumwalt] nailed it with his “Marblevator Line Follower.” Roboticists will immediately recognize a black line on a white ...

The little robot, about half the size of a small egg, whirs along on invisible wheels, using a camera on its base to follow any line it's put on. When it meets a branching path, it picks one randomly.