Yep, we need Rick!
I might be overthinking this but here goes.
Stuck on the idea of the witch's cauldron the rubber or plastic coating rules out anything with fire.
Okay, no fire. How about the fake flame electric fan cauldrons that hang?
And here is the overthinking part...
Back in the day before we had the electric fan fake flame thing happening, we just used dry ice to may the creepy fog happen.
But having dry ice in a metal container could be dangerous for curious fingers, so the solution is to add a coating or rubber/plastic to insulate the metal keeping little fingers safe.
That's my story and I'm sticking to it because if I don't I'll be at this all night.
