Most recently competitive barbecue masters have addopted the oil drum as a cooking instrument. Standing upright, with a wire mesh fire box at the bottom and a grill at the top, and a vent pipe which draws air into the fire zone at the bottom of the structure.
The fire boxes are ingenious. Mesh boxes with a mesh floor that could be moved up or down in the box to allow for more (or less) fuel. These are loaded with charcoal and placed in the bottom of the drum. They are generally ignited by a blow torch with an extension to reach the bottom of the drum.
The grate is near the top, just enough below the top to allow a lid to be placed on the assemby when the meat is in place. The lid has a smoke vent, with a cap to restrict the outflow of smoke.
Most are manufactured by the user from actual oil drums. One fellow I saw using such a device in a video was proud of the fact that the unit had cost him two dollars. I assume a serious cleaning takes place before these recycled oil drums are put into service.
The commercially produced units are drums that never contained oil, or anything else. They are new drums.
Now, I had a thought on this. If the drum were cut around the circumfrence about a foot from the bottom, the lower section would be available as a fire ring. If metal tubes were welded on at fixed distances around the circumfrence of both the top and bottom sections the units could be locked back together. To aid in this I would weld a strip of metal to the bottom of the top section along the inside circumfrence to aid in aligning and joining the two halves.
This access to the bottom of the drum would make lighting the fuel easier. Placing the fuel would even be easier. Plus, used as a fire ring, rods of metal could be placed into the tubes used to lock the two parts together and used to hold meat in place to roast beside the fire.
If one wished to do some dutch oven cooking, the tripod could be affixed to these points as well. The fire would be contained. The ash and other remains of the fire could be carried away with the rest of the gear, leaving a campsite clean and clear.
If I get around to drawing this up, I will place my drawings here.
At the present cost of these new drum smokers, I won't be buying one anytime soon. However, they are intriguing, and certainly I shall keep them in mind when I am ready to replace my Silver Smoker.