Big enough??
I made a wood stove on steroids out of a 275 gallon fuel oil tank a few years ago!..it had a 2'x2' door,and I stood it on end,bolted the pipe legs to the wall-
and cut several 2" holes in the upper portion with a hole saw and ran 2" pipe thru both sides and welded them in,an used a small blower motor to force air thru the pipes..it also had a forced draft air intake ,I used an old kitchen range "hood" fan thing to really get it cranking when lighting it,or burning wet wood or drain oil..the air intake was near the floor,about a foot up..I put old rotors and brake drums on the bottom to hold heat in from the hot coals..
It really cranked out some BTU's..we used it in a 155'x55' quonset hut at the junkyard..nothing would heat that building,but it did pretty good for 50' in every direction from the stove!...you could stuff half a tree in it at once,and it would burn most of the day,if you left the forced draft off..we could burn a tire or two with the forced draft on without much smoke!--but it would turn orange,and we warped it pretty bad doing that..that thing would melt a smaller garage!..used to put a whole pickup bed's worth of wood thru it in a few days!

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Another neat one we had was made from a huge ocean bouy..it was 6' in diameter!..someone junked 2 of them at the junkyard..we used one for diesel fuel for the loaders,and the other became a stove for awhile..we painted it orange and used it for a pumpkin out in front of the gate during halloween one year..everyone loved it!..
