Can not find a good 55 gal drum to make a rocket oven

I was looking around the other day for a 55 gal drum to make a rocket oven with and could not find one that was in good shape. I did see a few old water heaters with the outside metal in good shape. Could one use the metal shell of a water heater as an substitute for a 55 gal drum? I know from watch the Rocket Ovens DVD how the drum is used. Also I do not know if the metal from the water heater would take the heat or fail within a few years.

Many places to find a used 55 gallon drum: Oil change places, online classifieds, metal scrap yards etc. Usually with a bit of looking and a bit of patience, one can be found locally so don't give up.
The metal in a water heater tank is much thicker and therefore much heavier than a drum. I would say it would last longer because of this though. It is also smaller in diameter. So if either of these characteristics are not what you were looking for, then a drum is the way to go.