I found this on a great food storage blog, (safelygatheredin.blogspot.com) her blog entry had more extensive pictures of the process, but I think you can get the gist from this entry:
Did you know that you can make a cardboard box into an oven that works just as well as your oven at home? You can! And with this type of oven, you never have to worry about what to eat when the electricity goes out.
You need:
1 cardboard box (for this method, it needs to have a slide-on top, like a box that holds reams of paper. See pictures)
charcoal
matches (or a lighter)
aluminum foil
1 round aluminum pie plate (or anything to place your charcoals in)
3 wire hangers
scissors or a knife
pliers
tongs
whatever food you want to bake
Line the inside of your box and lid with aluminum foil. If you'd like, use a sponge and dab some Elmer's glue around the inside and cover to hold the foil in place (this is especially useful if you plan to keep your box oven, and not just make a new one in an emergency)
Once that's done, use some scissors or a knife to poke three holes in a straight line on each end of the box, about halfway down from the top. You'll see what these are for in just a minute.
Meanwhile, straighten out your three hangers.
Put the three straightened hangers through the holes. These will act as a shelf to place your food on.
Next, bend your wires so that they will remain taut inside the oven. We don't want heavy food bending the wires and sitting directly on the charcoals.
This step might be kind of difficult, so you may want an extra pair of hands and some pliers.
It doesn't have to look pretty, it just has to work! Next, poke some other holes in your box so that oxygen can get in and gases can get out. Now, we actually did NOT poke extra holes in this particular oven, because by the time we finished making our wires taut, our three holes we poked in each side had become fairly large, so we figured they were enough. If your holes on the side remain small, use your knife or scissors and poke a few holes on the top of the box, and maybe one or two on each side.
Place some charcoals in your round aluminum plate. Each charcoal briquette supplies 40 degrees of heat, so 9 briquettes will give us a 360 degree oven.
Light your briquettes with the matches or a lighter (it will probably take a few matches. Be sure that each briquette burns)
Let the briquettes burn for a while...Until they look like this! Then you're ready to go.
With your tongs, pick up the hot plate of charcoal and slide it carefully between your wire shelf onto the bottom of your box.
Place your food on the wire racks and cover with your oven top.
Now just set the timer like normal, or watch the clock. Note: If your recipe calls for a longer baking time (more than 45 minutes to an hour), you will probably have to switch out your charcoals around the 45-minute mark)
**Do not use your oven on a wooden deck or on grass, or anything flammable. We are cooking in a concrete deck. Never use this oven indoors.**
Wise counsel that the whole country should obey....
Avoid debt. … Today everything is seemingly geared toward debt. “Get your cards, and buy everything on time”: you’re encouraged to do it. But the truth is that we don’t need to do it to live. We wonder what our people will do who have been spending their all and more. If employment and income should reduce, what then? Are you living beyond your means? Do you owe what you cannot pay if times became perilous? Are your shock absorbers in condition to take a shock? Plan and work in a way that will permit you to be happy even as you do without certain things that in times of affluence may have been available to you. Live within your means and not beyond them. … Purchase your essentials wisely and carefully. Strive to save a portion of that which you earn. Do not mistake many wants for basic needs.
“Chapter 11: Provident Living: Applying Principles of Self-Reliance and Preparedness,” Teachings of Presidents of the Church: Spencer W. Kimball, (2006),114–23
