KGroce of Tennessee wrote in to share this sweet projector, built by Friedemann Wachsmuth:
A fully functional Super 8 Movie Projector I built with Kalle using Lego Technic. The only non-Lego parts are the lens, the reel spindles and the lamp.
The projector uses just two engines and is fully featured with automatic feeding, 24 fps, fast rewind and 120m reel capabilities. A decent LED flashlight makes it pretty amazingly bright.