When I was young I had no money, which sucked, because I also used to go camping a bit. I could always find someone to borrow gear off, but I lacked the skills to make a suitable source to cook on. A mate of mine showed me a little contraption he called a Hobo Stove. It was easy to make and did the job.
Below are steps to make your very own stove.
Step 1: The Can
Here we have a basic can of tomatos.
The best thing to use for this stove is an old can. You can find them anywhere and they are pretty durable. The size obviously depends on how big a fire you want and what you plan on using it for. (Larger can requires larger fuel source).
Step 2: Prepping the can
Strip away any label on the outside of the can, as it will quickly catch fire when lit. The next step is to make holes at the base of the can to allow air to flow to feed the fire. (You can make holes or cut away the middle around the top if you want, this allows items to be placed on top of the can without the fire going out.)
Step 3: Fuel
Scrap cardboard used for fuel
This stove uses two sources for fuel. Cardboard and wax.
The best thing about these items is they are pretty readily accessable and relatively low cost (Or free).
Get your cardboard and lay it out. You want it to be roughly as wide as the height of the can. The length will depend on how big your can is. Roll the cardboard as tightly as possible, adding more so that it fits tightly into the can without unrolling.
Adding wax to the stove.
Next you will want to use a candle (or another source of wax) and melt it over the top of the cardboard, Ideally you'll want to fill as much of the gaps with the wax. This will produce a steady and even source to burn. (Sure this uses candles but unless you have a lot of candles you won't be cooking anything anytime soon.)
After the wax cools, you are ready to light it up! The cardboard and wax burn together, creating an intense heat that is useful for more than just cooking. To extinguish you will need to completely suffocate or douse the tin. It will self ignite if not put out properly. For easier re-use, you can flip the cardboard and light the fresher end.
Prior to making the one for this article I created one of these stoves and used it to cook with. Mine burned for 7 hours straight, and it had only used half it's fuel. (It's pictured below.)