I don’t think a puffer lid is needed for charcoal, but I was not 100% sure when I started this. The Bain Marie is 4" in diameter, so I cut the hole for a tight fit. It was suggested that I buy a 4" pipe nipple and threaded cap, so I visited my local hardware stores, but they did not have any. I looked online, and with shipping, the two could cost 50 bucks! So, I went ahead and TIG welded the stainless pot into the steel propane tank using stainless rod. That rod flows like butter, and the weld looks good. I just hope something doesn’t crack later. I think I will try it out with an old Honda Generator, but the overall plan is to run a Honda 250cc twin cylinder engine (about 15 hp) that I bought as a wreck from a junk yard. (It has no front end.) I am in the process of building a utility sidecar that will hold the Simple-Fire, a Cyclone, and a Gilmore Filter, and a large car battery. Just need to graft a front end onto the engine…Martin Payne happens to have a frame with the engine removed, and it has the front end I need. I wanted a small hopper that I could pop open quickly, top off the charcoal, and close it back up. My grocery store run is 25 miles RT, on back roads which would provide a cooling down period while shopping. For the gasket, I have some sheet silicon that is 1/8" thick and very soft. Wife has suggested I buy a silicon cookie sheet from Amazon instead. The mating surfaces on the Bain Marie and the percolator coffee pot lid are very flat.