Instructions: https://rebrickable.com/mocs/MOC-187829/Raging%20Bull%20Creations/28-hour-pendulum-clock/
This clock can run for over 28 hours nonstop, then simply lift the weight and it'll run for another day! The clock itself is entirely made of LEGO, only the weight and string aren't , but they could be pretty easily. It's also quite accurate, about ± 30 seconds per day. Mine has been running for over 6 months nonstop, with almost no wear. Enjoy!!!
More MOCs are coming, so stay tuned!