I made one out off a large propane tank.It turned out great,much higher quailty than a drum.If you get to big it takes alot to it keep warm.I just marked out where the lid should be,and cut with my plasma.I purged it with water first then air.If you are worried about a explosion get some dry ice inside it before you cut.I used weld on hinges for the lid.It was the nicest smoker barbecue I have seen.When I was done with it I took it,and had it sandblasted to rid it of the smell.Which I should have done first.It was a whole lot more work than you would think it would be.Of course I got carried away.By the way I have welded gas tanks also.So a purge is good enough for me,but maybe not for you.