Hob Lipson and his colleagues at Cornell University have created modular cube robots or ‘molecubes‘ capable of self-replication. Each 10cm cube holds a microprocessor with a set of simple instructions and electromagnets. The scalable robots demonstrate self-replication (wma video 1, 2) by creating an identical copy of a formation of molecubes. Although the demonstration is crude in comparison to reproduction in nature, it shows that mechanical self-replication, given the proper elements, is possible. By reducing the size of the cubes and producing large quantities, the resolution of possible forms may reach that of gray goo.