Handheld 3D printing pens seem like a cheaper alternative to those giant autonomous boxes, but they require more patience than most of us can muster, and a decent level of artistic capability. This robot arm can help with the latter, by controlling where the pen can move to ensure better results. Like with a dedicated 3D printer, the Guided Hand system still requires a 3D model to work from. It won't improve your freehand creations. But if you wanted to recreate the Stanford Bunny, the robot arm attached to your 3D printing pen provides various types of feedback both guiding the motion of the pen, but also limiting where it can move.