http://www.slate.com/articles/video/video/2015/06/_3_d_print_bridge_3_d_bridge_robot_bridge_bridge_mx3d_robot_building_bridge.html

MX3D, a research and development startup specializing in robotic 3-D print technology, is hoping to construct a bridge over a canal in Amsterdam sometime this September using only two robots. They’d start on either bank and work their way towards each other in the middle, ejecting molten steel as they go, crafting their beams from multiple angles instead of on a more typical horizontal plane.