Maybe a food safe stainless steel or copper container with a silicon seal? Something like that would probably be at risk of exploding unless there's a pressure release vent I'd assume.

The other idea I just had would be to use a regular pot that's mostly submerged in the warm/hot medium being heated by the miner. This would actually mimic how crock pots function.

I think it needs to be more like a flexible membrane that can be in direct contact with the food, no air pockets.

Yeah, maybe I should just put the crock pot in there and see what happens.