https://www.cnbc.com/2018/04/07/mx3d-made-a-3d-printed-steel-bridge-in-midair.html >MX3D, a Dutch robotics firm, 3D printed a functional stainless steel bridge for pedestrians in Amsterdam's red light district. >The 41-foot-long bridge took four robots, 9,920 pounds of stainless steel and six months of printing to complete. MX3D combined an industrial robot, a welding machine and software to make the 3D printers.