Here is how I have been building Charcoal UDS. I have only been using used oil barrels, since I am still not sure what to think of the enamel liners in the food grade. I can usually burn the oil out of the drum with a good hot burn of charcoal with no lid. I tried to take the following pictures to better show how I am making them and hope I can help the next person expand and keep the world of UDS builds, ever changing and improving. In the pictures you will see how I just cut a hole in the bottom of the drum. The middle of the hole is at 2 in...use a 2 1/8 in hole saw and then place the pipe inside the drum approx 1 in and weld it into place. Been using the seam as a guide to keep the pipe straight. Another picture will show how I just use a piece of whatever metal is available to make a pivoting cover for the intake. Another picture will show how I cut the bottom of the weber kettle grill and then tack weld it into place, just enough to hold it and not warp anything. Lastly, a picture of my basket. It is made from the bottom of the grill with 3/4 in expanded metal for the sides, 8 inches tall. At the bottom of the basket you will see an ugly piece of metal. That is just a piece of very thin steel that I found in our metal hopper at work that I am working into holding the ash, so that I can just pull the basket out of the drum and dump to a awaiting garbage bag. I don't do anything fancy anymore, I leave that up to the person I make it for. That will usually give around a 14+ hour burn time if the smoker is kept around 240 degrees (+ - 20 degrees). Need to ask questions, send me a PM