Each unit comes with a small computer code carrying a blueprint for the layout of the robot, electrical contacts to let it communicate with its neighbours, and magnets to let them stick together.

By turning and moving, the cubes can pick up new units, decide where they belong, and stack them alongside each other to make new devices. In a little more than a minute, a simple three-cube robot can make a copy of itself. That offspring version can then make further copies.

BBC