It starts with those things that fall in your lawn from Gumball trees and clog up your lawn mower every year. You can see one pictured above, what is commonly known as a gumball. That will be your heat source. It is also advised that you allow them to dry for awhile before you use them - they don't work when they're green. Your oven, or stove top, if you prefer, is shown below:
You can see the first one in my tinfoil trough and the wax that pooled up below it when it was drying on the wax paper. It is okay to leave this wax attached to the gumballs as it doesn't affect it in any way and it saves time. Just make sure to use 2 gumballs for your heat source.
At the left edge of the picture, you can see a hole in my can. I knew the fire had to be able to "breathe," so I made four holes along the bottom edge of the can. But, once I had started cooking with this setup, I found it needed more air than these four holes would allow. I ended up making a little stand of twigs to rest the can upon, so as to get it up off the ground just slightly, and this worked great. So, the holes I made in the can weren't needed at all. You can save yourself this extra step for you won't have to do this to your cans. Another thing I found out is that if the wind is blowing, try to block it off with a log or something so it doesn't blow some of your precious heat out from underneath the open edges.
I did come up with an idea about continuous heat and it involves making a hole in your can, but I haven't tried it out yet, so it's up to you if you want to go ahead and do it yourself. But, I reasoned that if I had one hole near the bottom, (opened end) of my can that was big enough for some barbecue tongs to put a gumball through, I could always keep two gumballs burning and when one starts dying down, replace it with a fresh gumball. In this way, I figure I can keep constant heat going upward and this would allow me to cook something like stew or boil water for noodles - any number of things that have to cook longer than 10 minutes, which is all the time it took me to prepare my bacon and egg. Below you can see how I propped up my can so that the fire could get the proper air it needed: (You can also see the bacon as it starts to sizzle!)
By propping it up this way and having a lip around the tinfoil trough, (which allowed the heat to be funneled upwards towards the cooking surface), it also had the advantage of masking the fact that you're using fire to cook with. I imagine it would be next to impossible to see any light escaping from this cooker at night. This added benefit is probably a very attractive feature to some of you out there.
Above, you can see that the bacon is cooking quite nicely. After about five minutes, it ended up cooking about halfway done with the first 2 gumballs I had lit underneath it. When they began to die out, I turned the bacon over and put 2 fresh gumballs underneath and finished cooking. The bacon did tend to stick a little bit, so I had to be careful that I didn't burn myself as I was holding the can steady while turning the slices over. Good gloves or oven mitts are always welcome! Next time I'm going to try using some Pam or other cooking spray to keep my food from sticking. Be sure to use that when you do it, too, and that will make it even easier. The bacon had also begun to shrink by now, so there was room to put my egg on with it. This turned out to be just the right moment to do so, for the egg and the bacon finished cooking at the same time. Now, here's where I would have needed some gloves again, or some protection from the hot can. This method of cooking gets extremely hot, so be careful you don't burn yourself as you're taking your finished food off the cooking surface to your plate or lifting the can off to put new fuel in the tinfoil trough. That's why I think a good hole at the bottom would work well - that way you wouldn't have to keep taking the can off to put on new gumballs and losing some of the heat that you had built up for cooking. So, be sure and try putting a hole in your can for this reason.
Keep in mind that I didn't buy any part of this great experiment at Wal-Mart. You, too can shop and get everything you need without going to Wal-Mart.