this useful cool post was originally posted by Atman @instructables.com
You're going to need:
Two empty aluminum cans and one full one. The type matters very little, although there are some bottom-brand beer cans that are simply too thin to make a good stove; this assumes a 12 oz can although obviously the 14 oz tall cans work since I'm using one.
A single edged razor blade
Some number of thumbtacks and a nail
A piece of flue tape (ideal) or heavy gauge aluminum foil
A ruler, book, and sharpie marker
Your life will be made easier by a hammer and a pair of scissors
Go around the burner puncturing every other hole with a thumbtack, then go around again to get the rest of them. Be careful in this and other steps not to dent the can any more than necessary, handle towards the top and bottom and put pressure as evenly around as possible. The thumbtacks will bend, some of them, so you'll be going through a few.
Taking the bottom section, press it over the jig and remove. This part is tricky; lubricant would help but I confess I haven't bothered as the aluminum is just that smooth. You can get a bind but if you screw in and down then out and up without stopping you can jig it smoothly. Do NOT dent the rim at this stage; if you do, carefully smooth it on both sides with a thumbnail.
Now, put the middle piece into the top piece as before, and fit the top piece so it slides inside the bottom piece. I use a shim, made by smoothing a cut piece of can with sandpaper, to fit these pieces together. It takes practice, and is the hardest part of the project; you will really benefit from undented pieces at this stage of the game, but I've assembled some pretty sad looking pieces with a little patience. Once together, push the top down into the bottom until the middle wall engages; this often includes a 'click' noise that makes it clear that you've done the thing to the nines.
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