Here's another effect originally featured in a small Quonset hut on the White River & Northern IV. It's a simple effect: I use Dremel ball grinders mounted to gears driven by a low-RPM motor. That's it.
The new mechanism had four vents, which meant a lot of gears. The gearing makes some vents spin a little faster than others. I'd also planned on making an electronic control to vary the motor speed randomly.
I installed the mechanism in the brewery building on 27 May 2020.