We gave covered plenty of cool 3D printers here in the past. The Guided Hand 3D printer is quite intersecting though. It uses a haptic feedback design to bring accuracy to printing process with a 3D pen. The Geomagic Touch is the haptic feedback device that produces the sensation of touching models.
Guided Hand allows designers to produce more accurate models with a 3D pen. The above video shows what you can do with something like this.