Carbon fibers strength and lightness have made it the material of choice for everything from spaceships to computers to violins. But so far, there hasnt been a 3D printer that can print in carbon fiber — until now. The Mark One, announced yesterday (Jan. 28), is a compact but high-end 3D printer designed to print objects as large as 12 by 6.25 by 6.25 inches, all in carbon fiber.