3D pens are nothing new. Many use them to build models quickly. They are not always easy to control or accurate. The Guided Hand 3D printer is a robotic system that allows artists and designers control a 3D pen in a more efficient, accurate manner. It relies on a haptic feedback device, the Geomagic Touch, to allow users the sensation of touching digital models.
The above video shows how Guided Hand works. Yelizk.com has more on the story.