I am thinking about using this cast iron door off an old wood/coal stove. I set it up for a basic layout with cardboard to the CC for the smoker. I don’t think the size is to bad and I will be using my own air intake instead of the one on the door. If u want to follow my build here it is. https://www.smokingmeatforums.com/threads/added-pic-my-first-reverse-flow-smoker-build.325107/