Heber:
A couple of things I have thought about are as follows.
I think the height from the bottom of the can to the top should be at least 2 inches so the hottest part of the flame inpinges on the pot. Next, I think there should be a rather large opening at the bottom, perhaps a square 1" by 1" so you can stick a wooden match in and light the tablet once in place. This would also allow quite a bit of air in, but still I would drill holes around the bottom to assure good air flow. The large opening would be down-wind when the stove was in use. The final point is that there needs to be enough holes, and large enough, very near the top. This is so there is good air flow out. Actually as the air comes in and gets burned it increases in volume. When I experimented with this the first time I didn't have enough or they weren't large enough because the flame was not as large or bright with the pot on the stove. JIM
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Jim M