In the future, your local public works department might use a small, wheeled robot to repair potholes on city streets—assuming this recent Harvard graduate's idea gets funded.

Robert Flitsch is the inventor of the Addibot, a 3D-printing robot that uses raw material to build surfaces up layer by layer, much like a boxy, desktop 3D printer would, but without the same space constraints. It can steer itself, or be driven via remote control.

"One of the main limitations with 3D printers is you typically have it printing inside this box, and you can really only print objects of the size of the workspace you're printing in," says the 22-year-old Flitsch, a mechanical engineer who graduated from the Harvard John A. Paulson School of Engineering and Applied Sciences last May. "If you take additive manufacturing implements and make them mobile, you can print objects of arbitrary size."

Underneath the chassis of an Addibot is an array of nozzles that, ostensibly, would lay down materials as needed to repair a variety of surfaces. Flitsch, a longtime hockey player, first tested his Addibot on ice, the idea being that such a robot could deposit water, with a temperature just above its freezing point, into the cuts made by skates on hockey rinks, and then freeze once coming into contact with the ice surface. So long as the width of the print array accurately represents the crack or hole the Addibot is passing over, the repair work could be done at a constant speed "on the order of a few miles per hour," says Flitsch.