I recently made a great gas forge for knife making based upon the designs by Larry Zoeller. His web site includes all the necessary information for constructing a few forges from coffee can size and up along with all the specs and measurements you'll need and its all free on the internet. He also supplies pre made burners (in whole or part) that work on a venturi principal requiring no added air supply along with all the other components short of the metal forge body. For mine I used a piece of twelve inch diameter half inch pipe which I believe was a well casing and about eighteen inches long and welded up the door,hinges, back and base from some scrap plate steel that I had lying around. I purchased the complete burner kit and tank hook up kit from Larrys web site all the rest cost me was time and welding rods. Google 'zoeller gas forges' and good luck. Tom Coles