Spotted at Hackaday is a link to a flip top display built entirely from Lego.
The display is programmed by arranging single-unit bricks on a template to either turn on or off a pixel. A set of fingers raise up, the new template slides in, and the fingers are lowered onto the template to set the display dot discs
The article links to youtube videos of the complete display in action and a single pixel mechanism showing the on/off sequence.
There is detailed information on the way it works in this forum posting, which links to further information on Chebyshev's Lambda Mechanism and the Dwell Mechanism used in the construction of the feeder.
(Score: 2, Interesting) by inertnet on Sunday April 26 2015, @11:58AM
I've seen some "water gates" like AND, OR and flip flop made with water. It was about 35 years ago at a "world science fair", can't remember the exact name right now.