I like to tinker, so I tried my hand making a coupla' homemade smoker tubes.
I bought a sheet of #8 X .035" grade 304 stainless steel screen. I cut three sections, rolled them and fastened the seams with hog rings. One end of each tube is closed with three crimps.
The largest (top in photo) is 2" X 18", the next one down is 2" X 12" and the smallest is 1, 1/2" X 12".
I got a four hour burn from the smallest and a six hour burn from the medium size. I have not fired the largest yet, but expect an eight hour or better burn from that one.
The smallest one produces about the same amount of smoke as my 5" X 8" AMNPS. The medium size produces almost twice as much. As the largest is the same diameter as the medium size, I expect about the same amount of smoke, but longer.
I did not leave an ignition hole in the closed ends. Rather, I held the torch to the screen at the closed end and the heat transferred through and lit the pellets. There was almost no lag time in getting the pellets lit.
When I put the first tube I built (the smallest) in my Masterbuilt 44, I laid it so that the open end was slightly elevated above the closed end. It burned well, never went out and never went to flame.
These tubes are nowhere NEAR the quality of those that Todd makes. For that matter, personal opinion, NOBODY produces a product as good as Todd does. It was simply an experiment to see if it would work, that's all. They do work.