Mechanical Marble Adding Machine

A single-file HTML 3D marble computer that pays tribute to Wintergatan's marble machine and the Digi-Comp II. It adds two 4-bit numbers using only marbles rolling over mechanical flip switches, and the result is read from the switch states. Wooden board, brass toggles, and glass marbles under warm lighting, with an automatic DEMO mode and click sounds. The finished video is a screen recording of the interactive demo. Well suited to explaining how computing works and showcasing 3D technology.