Hello howardz71, I haven't seen plans for a charcoal cooker like that but sounds like it really works. I use a 55 gal drum with a 4" x6" door cut close to the bottom and a lid that fits loosely. Then about 4 or 5" above that I drill and insert 2 1/2" rebar rods to hold an inner barrel ( an old transformer casing ). The inner barrel has a bolt down lid and 6 3/8" holes drilled in the bottom. I like this cause the fire is enclosed and the brush don't catch as quickly. I use the door on the bottom to stoke the fire and I can see when the flames die down coming out of the holes in the bottom of the inner barrel. When that happens I just pull the rebar out and drop in the ash of the outer barrel. Let cool down 5-6 hours and you have charcoal. I really would love to have heard it when the volitals started catching. People ask me why I make charcoal and I tell them cause I can. Good luck