Robotic arm 3D printers are cool. Really cool. Instead of printing within a box, they can build towering structures. They also aren't limited to the layer-by-layer approach of the average consumer printer; they're freeform. They're common in manufacturing, but why aren't there any available to the average 3D printer user? A few experts offered up their opinion.
Cornell engineering professor and "Fabricated" author Hod Lipson: