Retro Thing: The Tinkertoy Computer:
This brilliant Tinkertoy digital computer was built by a team of students at MIT in the 1980s. It's a marvel of mechanical design that apparently plays a "mean game of tic-tac-toe." The idea was born in 1975, when two Sophomores worked on a class project to build something digital from Tinkertoys. It took another few years before they collaborated over the phone to design a working machine for the Mid-America Science Museum:
"A Tinkertoy framework called the read head clicks and clacks its way down the front of the monolith At some point the clicking mysteriously stops; a "core piece" within the framework spins and then with a satisfying "'kathunk' indirectly kicks an 'output duck,' a bird-shaped construction. The output duck swings down from its perch so that its beak points at a number- which identifies the computer's next move in a game of tic-tac-toe."