Cool Stuff: PriNXT Lego Printer
The PriNXT by Leon Overweel is made from Lego’s Mindstorm system that lets you add motors and some programming magic to your Lego projects.
Even though he's just 14 years old, Leon managed to build the PriNXT along with a number of other Lego projects--including a Skype-controlled Lego Car.
The printer essentially works like a traditional dot-matrix printer. A series of motors, controlled by the NXT set, positions the print-head (a marker in this case), and then steps it down to touch the paper to create one dot of the overall image. It then repeats the process until the image is completed.
(vía: PCWorld; source: World of Mindstorms)