These mini robots are called “kilobots” and only measure a couple of inches across while standing on three wire thin legs. While these kilobots are quite simple as individuals, they are able to work together in ways whihc allow them to perform complex actions and tasks. So while a single mini robot can’t do much on its own, when a group of them are together with some basic information programmed into them, they can perform more complex actions:
Even mistakes can’t hold them up. If, while attempting to create the shape, a traffic jam occurs or one of the robots goes off course, the others sense that there’s an issue and cooperate together to fix it through an infrared transmitter which allows each bot to communicate and measure its distance with those within a certain range of itself.
You can also build your own mass army of these kilobots. The information you need to build and program your own kilobot has been published, allowing anyone to play and experiment with what these hive-minded bots can do.