These have worked great for me-----use them in my grill----cold smoke ----hot smoke. I'll give you a ballpark figure on time-----the 12 in., 4 to 7 hours----seems to depend on pellet type, humidity and draft.
So anyway, I'm going to try to show you, mostly with pics----it's simple but harder to explain-----I'll try to answer any questions.
First of all I purchased some easy form welded wire mesh, 304 stainless. I got mine from McMaster Carr (they sell small amounts without breaking the bank.
https://www.mcmaster.com/#wire-cloth/=17dm5uc You want the easy form ----4x4----0.222----78%---0.028---9322T66---$9.52 a SQ. Ft. You can get two 12 in. tubes out of 1.
Originally I was going to show some pics using the !/4" size. Decided it was to hard to show the details, so I went with a 1/2" mesh to better show how it's done, bear in mind this is much bigger then the !/4"
Use the dykes to cut the 12" mesh in half--leave the prongs on both sides.
Wrap the mesh length wise around the 1 1/4 " dowel (hint the dowel is what used to be used in roll up blinds) seems the best size I've tried.
Bend the prongs around using needle nose pliers and small screw driver, try to offset the next wrap to give about a 1/8" square opening on bottom half of tube.
You can use a hose clamp or duck tape to hold while you bend the other prongs around. In fact, you can use two hose clamps placed about an inch and a half from each end and call it done -----it burns just as well and is much easier to do -----just doesn't look as good.
Make 3 or four radial cuts on one end and hammer inward to close up the end.
I make an aluminum ash catcher and a small stand for better air flow----keeps the mess down, especially in the BBQ grill.
There you go--- takes me about 30 minutes to make one.
I retrospect-----when I first made these, the commercial products were about $ 19 to $40.00. I'm just plain cheap and I like to recycle, had the stuff laying around for the first one----liked it ----made more. Now I see some versions going for $15.00---BUT I"M STILL CHEAP
Blaise