Mike Davey, a maker from Wisconsin, built a classic Turing Machine with a 1000 foot instruction tape that holds up to 10k. Though Turing's machine was just a thought experiment, the paper in which it is described has enough detail to create it in real life. The machining is absolutely lovely, and when it's in motion, it's a thing of beauty.
DIY Turing Machine (IEEE Spectrum))
(Thanks, Erico!)