I usually use 16 ga.galvanized sheet metal--I get it from the local landfill's scrap metal pile--seem someone is always tossing a heating duct out made of that--it lasts a long time,but be careful welding or brazing it--the fumes can make you very ill.I've also carted home a few washer-dryers,and refrigerator-freezers to carve patches out of for my trucks--the epoxy paint holds up good against salt and weather,best part is its all FREE!,leaving you more money to blow on welding rods and other stuff. And the "tub" out of the clothes dryer makes a perfect fire pit for backyard bar-b-q's and keg parties!. /forums/images/graemlins/crazy.gif