Turing Tumble is a mechanical computer created by Paul Boswell in 2017, operated by marbles. It is targeted for education, but with a big enough board could allow to build any contraption and is Turing Complete.
Marbles move down the board by gravity, controlled by 6 types of parts you can add to the board. When a marble hits the bottom, a new marble from the top is released. Two types of marbles can be released, blue or red.
|ramp||moves the marble left or right|
|crossover||allows marble to keep moving|
|interceptor||stops the program|
|bit||toggle between left and right state and sends marbles in alternating directions, operates like a T flip-flop|
|gear bit||bit that can be connected with gears, this component makes it Turing complete|
|gear||connects gear bits|