I am new to the smoking meats forums and have started my first build. I am using a propane tank like most everyone else but for a firebox I will be using an old air tank. I have run all the numbers using faldons and am ready to cut the firebox to cook chamber open in. Being that my opening is two rounds overlapping for the circle calculated I found a figure for half the opening I will need and then plan on just marking half then flip it over my template and get the shape for two overlapping rounds. I know this may sound confusing. Will it work? By the way I need about 86.86sq.in. for an opening and my rounds are 24in. In diameter. Any advise would be great.