I've got a metal (stainless?) box from Coghlan's that has a rubber gasket in the lid & two (2) clamp/latches to secure it. The bottom could be used to heat water in. I looked at their web site yesterday, & couldn't find it, though, so it may no longer be in production.

I've also been given a candy tin that is quite similar to the tobacco boxes I've seen, except instead of bare metal, it's got colorful graphics on it. It, too, has a rubber gasket around the rim of the lid, not the bottom. Heating this type of container would not harm the gasket, because it's in the part not being heated.

Just my 2 cents...

David