I have a 37in propane lid (half a sphere) and a tractor rim that is 37in with a 3/4in lip. The rim is about 24in tall. The sphere fits right on top tight. I'm thinking about using it for the inside of the oven. Wrapping it with insulation and then bricking around it. What stone to use, insulation, how thick, what kind of floor? Up for all suggestions. Thanks.