The emergency heat source preferred by Scouts, WW II GI's, and homeless people everywhere.
THE BUDDY BURNER
Materials: Plain corrugated cardboard (not printed with bright inks or coated with wax or plastic) flat tuna cans, flat pet food cans, and/or flat pineapple cans, and their lids #10 can (the large institutional size) candle wax or paraffin.
Tools: punch-type can opener tin snips
Cut the cardboard in strips whose width is the height of the can -- across the corrugations, so that the holes show. Roll the strips until the cardboard roll fits snugly into the can.
Melt the wax. It is best to use a double boiler, as if the wax gets too hot, it can burst into flame. You can improvise a double boiler by putting water in a large pan, and then setting a smaller pan into the water. Each tuna can will take about 4 ounces of wax.
When the wax is melted, slowly pour it into the buddy burner so that it runs down into the holes and saturates the corrugated cardboard and fill the can to the rim. You can put a small piece of cardboard sticking up or a candle wick in the middle to help start it, but this isn't required. Let it cool and harden. To light it, set it on a brick or concrete block. Put a lighted match in the middle of the can or light the wick. The flame will spread across the top of the can; that's OK, that's what it's supposed do.
To use for cooking: Cut out one end of the #10 can. Use the tin snips to cut a 3" high and 4" wide "door" on one side of the can at the open end. Leave the top of the door uncut. Bend this flap of metal up so the door is "open". Take the punch-type can opener, and make 3 or 4 holes on the other side of the can at the top (this is your chimney). Light the tuna can as described above, and place the #10 can over the Buddy Burner and place a pan with whatever you want to cook on top of the #10 can. This "#10 can stove" can be adapted to fuels like twigs, charcoal or charcoal briquets, but these shouldn't be used indoors. Charcoal briquets shouldnever be used indoors under any circumstances. The fumes will kill you before the cold does.
To regulate the flame for heating or cooking, use the can lid as a damper. Place it over all of the flame to extinguish the fire, or cover it partially to regulate the amount of flame. You can also use a piece of aluminum foil (several thicknesses folded), that is larger than the tuna can. Handle the damper with a pot holder, or a pair of plyers, or punch a couple of holes in the edges of the lid and use some wire to make a handle.
To refill the buddy burner, place small amounts of wax on the cardboard while the burner is operating. As long as it has wax, it will function.
Baking: Using tuna cans as little pans, anything you would bake in a regular oven can be baked on top of the #10 can stove. Simply place another #10 can over your baking pan and its an oven!
Emergency heat: Don't put the #10 can over the buddy burner, as it makes more smoke with the #10 can than without. Light the buddy burner, let it warm up a room and remember that it is easier to heat a room than a house, and it is easier to heat a room if you are bundled up warmly. Which is to say, a winter no-heat emergency is not a time to expect that you can walk around the house barefoot and in shorts. As soon as the room is warm, extinguish the buddy burner.