Create interactive structures with cubes and marbles

A question that haunted me for many years is: "how to make a computer out of mechanical parts"
By "a computer" I don't mean a 1-to-1 replica of an electronic device, nor a Babbage-style contraption: they will both be too complex to understand and difficult to operate.

I'm more interested in the logics of a computer: boolean operations, moving bits around, and similar things ... perhaps even something more related to Turing Machines, with a large storage, and possibility to read and (re)write the symbols in the storage (represented by marbles eventually)...

Anyway: I've found a great toy that also embodies many concepts related to a "mechanical computing machine".
The name is Q-BA-MAZE.



It reminds me also of an interesting toy sold in the 60es in the USA, called DIGI-COMP II (see here for a reconstruction made with lego). Another article related to the DIGI-COMPs is here.