Matt Sullivan, a retired soldier, still has trouble explaining his right leg to strangers.
The shiny chrome surface, embossed with the lightning bolt logo of his beloved San Diego Chargers, covers the calf area of his prosthetic leg, the result of a roadside bomb in Afghanistan in 2010.
At the naval hospital where he was recovering from his wounds and the resulting surgery, Sullivan ran into entrepreneur Scott Summit, who suggested a solution to covering the metal rod that protruded conspicuously from his knee.
Summit's firm, Bespoke Innovations, uses an obscure process known as 3-D printing to make durable thermoplastic leg coverings, or fairings. By digitally scanning the surviving leg to match its shape and form, Bespoke produces curved panels resembling soccer shin pads that cover the artificial limb. You can often tell a person has a prosthetic leg by the way the pants leg flaps, Sullivan says. "Having that symmetry now, you can't tell the difference."
How could you create a business using 3-D printing?