Insulating the cooking chamber.
For the top and bottom of the cooking chamber I lay out 4 sheets of HD foil 12.5 feet long, on top of each other, I then folded the one edge over twice to seam all 4 layers together. Then folded 2 of the layers open giving me 2 layers of foil 12.5 feet long and 32 inches long, which is 2 inches longer than the cooking chamber. I marked the 12.5 feet length at 32 inch marks, this is the radius of the cooking chamber. Folding the foil at the 32 inch mark I ended up it a mat that was 32 inches wide by 32 inches long, and 10 layers thick.
For the top of the cooking chamber I rolled the mat into the top and cut a hole for the smoke stack. Because the mat is 32 inches wide and the cooking chamber is 30 wide the edges over lapped to the sides of the chamber.
For the sides of the chamber I cut half circles of 1/8 SS sheets the size if the sides. I uesd the bolt that were there for the warming rack to attched the rear of the half circles and added 2 1/4-20 bolts to attached the front.