\"Kitten Stove\" - Step 2

Step 2 - Punch holes along the top rim of the can.
Make these holes as close to the edge as possible. These holes should be snug against the ridge on the rim of the can.

Edit: Subsequent experiments have shown that not so many holes are needed. You need about 8 holes. I made one with 16 holes, it looked a bit nicer and worked just as well. Photo here: http://www.whiteblaze.net/gallery/showphoto.php/photo/5834/sort/1/size/medium/cat/516/page/