We have one that is made out of a tank. Its 12feet long and prolly 5' indiameter. Its heavy. It has trays on it for beans, and all kinds of stuff. the smoker is at the back.
We also have a few built out of 36" pipe. they work good for bar-b-q grills, and just get an old barbq for the burner.
In the big smoker, we can use propane, wood or charcoal. the propane burners are home-made, and have orfices in them.
Let me find some pics... ... ...
--Jeff