thin plate will do .it will need to be an open vented system thoughi have made a fire for the workshop out of a large gas bottle, i am looking to add a water jacket to it so i can add rads, do i use the same thickness metal as the gas bottle or would it be better in thin plate as i am only using a wolf 140 welder
cheers
Somewhere on this forum theres a load of pics from someone that has allready done this.