One-bit Mechanical Marble Computer
Heather, Zach and myself created a one-bit mechanical adder (with a carry function) that runs on marbles. I found the basic design online and we modified it to our purposes. Zach and Heather used cardboard, foamcore and genius to prototype the flip-flop mechanism, then mounted each on a cardboard box, adding ramps and chutes to carry the marbles through the system. The flip-flops tilt to the left to indicate zero, and to the right to indicate one. So the top indicator denotes binary 1, while the bottom indicator indicates the carry bit, or binary two. Here’s a movie that I made of the adder in action, before I decked it out in rave-wear.
The plan going forward is to implement the design in wood, with additional bits (maybe eight or 16) and a subtraction function. It would be interesting to add a crank mechanism that carried the marbles back up to the top, perhaps in a single turn. This would allow for multiplication.