Some readers may recall building a line-following robot during their school days. Involving some IR LEDs, perhaps a bit of LEGO, and plenty of trial-and-error, it was fun on a tiny scale. Now imagi… ...

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.

It is able to follow a dark line on a light surface based on how the infrared beam reflects back to the detector. But it’s a one-trick pony that [Eric] wanted to make into a programmable robot .