The HitchFire Ledge provides a platform that fits a two-burner...
A key tenet of survival is working with limited resources, and making do with what you have or what you can find quickly. In urban scenarios, this may mean scavenging or even dumpster-diving for supplies.
Obviously, unless you're desperate, you probably won't want to eat food directly from a dumpster—but there's another important resource you can find in trash heaps: empty tin cans. One or two of these items can be used to create what's known as a “hobo stove” for heating food or boiling water efficiently.
The hobo tin can stove is about as simple as it gets. Find a large tin can, such as a coffee can or can of beans. If it's not already open, you can remove the top easily in most urban environments with the concrete can opener method. Then…
Here's a video that demonstrates the basic hobo tin can stove. The host uses power tools to cut the fuel hole quickly, but you can easily do it with a knife or tin snips and a little patience.
The one downside to this simple tin can stove is that it creates a lot of smoke, and may give away your position to others nearby. If you want to avoid the smoke, you can modify the design to create what's called a “gasifier stove”. Gasification causes the fuel to burn at a higher temperature, leading to cleaner combustion and less smoke.
To create a gasifier stove, you'll be nesting a small tin can inside a large tin can, and drilling the holes more strategically. Here's a demonstration of how to make a wood gas stove:
Regardless of how far you take this simple design, the fact remains that it uses only a discarded tin can (or two). That means it's easy to create in the field, and even if you can't build a full campfire, you'll be eating hot meals again in no time.