Jason Allemann built a neat LEGO Drawing Machine, inspired by a Spirograph and a 1950s toy called the Hoot Nanny or Magic Designer.
It can create many different patterns by changing the configuration of the model," Allemann writes. "You can also draw multiple patterns on the same piece of paper to create even more complex designs."
He's posted the building instructions on his site JKBrickworks.com.
(via Laughing Squid)