I posted in 2011 about the Digi-Comp I, a 1963 mechanical digital computer made of polystyrene and used to teach the fundamentals of boolean logic, binary, and computer programming. I'd just discovered that Evil Mad Scientist Labs sells a wooden version of its successor, the Digi-Comp II, which uses a pachinko-style marble-run to do the same thing (the Evil version is CNC-milled and laser-cut). They call it a "Rolling-Ball Binary Digital Mechanical Computer." It is both beautiful and very clever indeed.
Overall, it is slightly smaller than the original (mid 1960′s) Digi-Comp II, which used half-inch diameter glass marbles. Rather than marbles, we’ve opted for pachinko balls, which are shiny steel balls 11 mm (about 7/16") in diameter. Using the smaller size has allowed us to reduce some of the feature sizes, and reduce the overall size of the machine from 14×28.5″ to 10×24", while retaining all of the original functions and remaining finger-friendly.
The Digi-Comp II: First Edition is CNC carved from rock-solid half-inch hardwood plywood, laser-engraved to provide it with labels, and hand fitted with over 60 laser-cut parts. It comes assembled, tested, and ready to use.
It sells for $279.