Hey guys and girls. I'm needing to build some smokers. I looking at building 2 smokers at the same time. 1 for myself and a 2nd to sell. I would like to start building several a year to sell. This is something I've wanted to do for a really long time. The 1 I'm keeping is a 150gal propane tank and the other for sale is a 120 gal air tank. Every smoker I see I look at how it's made. I've been keeping track of ideas for at least 5 years now. My problem is on the math. I'm not sure on the drop down of the fire box v/s cook area and the drafting. Any help would be appreciated. Also is any Facebook forums or pages I can join.