Thanks for all the info folks.
So if I build the forge with a inside measurement of 5 inches wide by 5 inches high and 9 inches deep would work for a single natural aspirated burner. I was thinking of working out from my measurement and I was worried that I would get to much heat lost through only 1 inch of ceramic board that will be treated. For the outer walls I was thinking of 16 ga. sheet metal and I want to be able to take the forge with me when I go camping so if I can keep the weight down all the better but it needs to be safe as to not heat up surroundings. I am new to blacksmithing and have been using a paint can forge but the lining started burning out so this is why I am looking for a new forge and asking all these novice questions.
Flint