I have the body of my forge welded up. I used pipe about 1/4" thick and is 8" wide and 9" deep. I got ceramic blanket, Plistix and Kast-o-lite 3000 from Wayne Coe. I plan on having a floor from the Kast and also to use it to line the blanket, at 1/4-1/2". If I have my numbers right, one layer of blanket gives me inside diameter about 6" with rough volume of 225 cu/in. 2 layers give about 4 inches and around 100 cu/in. (Both would have one layer on the back) This is before the Kast. I have a 3/4" burner. Am I making the inside too small with the two layers?