Take a 6 oz juice can. Cut the top out, leaving the rim in place. Mark the can with a sharpie all around 2” below the top and 1.25” above the bottom. Cut carefully along the lines. The scissors on the small Swiss Army Knife work well for this. Make 4 uniform crimps on the cut edge (bottom ) of the top, folding the aluminum toward the center. These are big crimps or flutes that go from the bottom edge to near the cut-out top. Fit the crimped top into the bottom with the original top upward. The crimps will rest on the domed bottom of the bottom piece. Finally, very important, make 4 holes about as big as nail holes between the crimps on the top piece about 1/2 inch below the top. Put a full cooking pot on the burner to make sure it sits securely. If not, check the flutes to make sure they are resting uniformly on the bottom. That’s it!
Test OUTSIDE with 1 oz of denatured alcohol and your cooking pot. This is best done in dim light because alcohol flame is invisible in bright light. When you light the burner, watch for about 3 seconds before setting the pot on it. An amazing thing happens— the burner will start generating flames from the flutes, aggressively! Now set the pot on.
This burner will boil 750 ml of water reliably with less than 1 oz (30 ml) of denatured alcohol .
A trick to save fuel: heat water to only 150F. Everything will rehydrate or cook at 150 if you put the food in a cozy to finish cooking. 150F will also sanitize drinking water. McMaster-Car has adhesive, reversible temperature strips. About $20 plus shipping gets 10. They last. Put one about half way up the side of your pot. Usually 1/2 oz (15 ml) or a smidge more will do the job.
The only source for adhesive, reversible temperature strips I have found is: McMASTER-CARR Reversible temperature strips. #59485K26, Range: 77-212F and 25-100C. $20.38USD/1 pack of 10.
Temperature strips on Amazon are for medical, brewing or aquarium use and do not reach 212F.