re: Building a new smoker-Finished

I'd definitely go with 11ga instead of 1/4". And for one of the walls, prob the outside, 1/6" is plenty. It'll save you money, be lighter and last forever if you paint it.

Metal isn't going to hold in heat. It just acts as a big heat sink, taking you longer to get up to temp. It may help in moderating temp changes, but that is what the insulation is for. Just my opinion.

Looks like it will be a sweet smoker though.

Oh and another thought, it took me a long time and a number of smokers built to figure out that the internal dimensions work really well if you can slide standard steam table pans onto the rails.