This is the tin can twig stove hoboes have used for cooking since time immemorial.
It's quick to make, easy to light, and does a lot of cooking with mere handfuls of twigs for fuel.
It doesn't make much smoke or shine much light, in case you don't want to be found.
It also doesn't leave fire scars or start forest fires very well.
That's good for both fugitives and environmentalists.
Another tin can would be the cooking pot for a living-history hobo re-enactment enthusiast. Preferably with a piece of wire through two holes through the lip to hang it like a little bucket.
Here's my favorite can for a hobo stove, a 3 liter olive oil can. I'm cooking salmon heads and giblets into soup on a driftwood pile in the rain in British Columbia. I consumed the olive oil during the weeks it took me to learn to catch salmon. This is a new stove, the paint hasn't all burned off yet, and it needs more air intakes. With just one door there will be charcoal left in the ashes. With three doors everything gets burned, and it's easier to feed fuel.
Step 1: Don't Do This
The hobo stove and some common sense will leave your campsite looking like wilderness.
Here's what bad camping leaves behind.
Please notice the pile of crap and toilet paper just behind the fire scar. Rain has washed the sand off the top of it. The bacteria washes down into the oyster beds and the tribe won't be able to sell their oysters. In this area you're supposed to crap or dispose of crap in deep water in the current, or a couple stone's throws from the water in a > 8" deep pit.
Strange to say, but kayakers are the bad guys in this case, much worse than power boaters even.
In case you're tuning in late and want the current eco-dogma,
shellfish farming is usually good for the environment, whereas salmon farming is usually bad.