Nick Leindecker of the Stanford Optical Society shows Laser Craze, a laser cutter that is controlled by two knobs much in the way an etch a sketch works. At Maker Faire Bay Area 2011 he allowed attendees to try out his invention on various burnable surfaces, while also showing his LED creations.

http://photons.stanford.edu/
http://makerfaire.com/pub/e/5042