For the printer to work efficiently, the focal point of the lens would have to be trained right onto the surface of the sand. He knew the sun would move and the focal point would shift during the process, so he ordered a single 4.5-foot-wide lens and built a motorized frame for it. The central sandbox, in which the objects are printed, shifts in all directions, and the entire machine rotates around its center. Two aluminum arms, holding the lens at one end and solar panels at the other, can pivot from straight overhead down to a 45-degree angle to chase the sun. directed by a CAD design from a connected laptop, the printer uses the concentrated beam of sunlight to slowly trace an object into the sandbox layer by layer. The sun melts the sand, which cools into glass.