Sounds like a good exercise. Start with a fixed‑point wind turbine, maybe a 3‑blade fan that turns a central shaft. Attach a simple ratchet on the shaft so once it spins it keeps turning. Now for the puzzle: use a set of interlocking gears that can only be meshed in a specific order. Give each gear a unique tooth count—say 12, 18, 24, 30. The trick is to arrange them so the smallest gear drives the largest without slipping. Keep the shafts parallel, no cross‑linking. Once you get that lock‑in, the turbine will spin and the grove will light up. Try sketching just that, then build a small mock‑up with cardboard. The real challenge is to make the gear train self‑correcting—if you swap two gears the system stops. That’s the puzzle. Good luck.