Jonathan Bachrach, an MIT researcher, has developed a fabrication machine that will assemble real structures based on digital building blocks — a Lego set for grown-ups.

Once the outline of an object has been determined, the system overlays a 3D grid and assesses which cells will touch the exterior. Then it assigns a particular block shape to each square and decides on its orientation, so that a digital assembler can build up the object.

The machine is a cross between a 3D printer and a rapid-prototyping machine, with the advantage that once an object has been created, it can later be broken into its constituent parts. The pieces can then be reused to make something new.