"It's been a tough slog in some ways, but we're at a tipping point," says Dean Kamen, founder of DEKA Research & Development, who holds more than 440 patents, many of them for medical devices. In labs around the world, bioengineers have begun to print prototype body parts: heart valves, ears, artificial bone, joints, menisci, vascular tubes, and skin grafts. "If you have a compass and a straight edge, everything you draw is a box or a circle," Kamen says. "When you get better tools, you start thinking in different ways. We now have the ability to play at a level we couldn't play at before."