RepRap is short for Replicating Rapid-prototyper. It is the practical self-copying 3D printer shown on the right – a self-replicating machine. This 3D printer builds the parts up in layers of plastic. This technology already exists, but the cheapest commercial machine would cost you about €30,000. And it isn’t even designed so that it can make itself. So what the RepRap team are doing is to develop and to give away the designs for a much cheaper machine with the novel capability of being able to self-copy (material costs are about €500). That way it’s accessible to small communities in the developing world as well as individuals in the developed world.