What You Will Need: Box with top flaps cut off (the box will be inverted, making the bottom of the box the top of the oven) Box should be about the size of the old-style computer monitor box or about 2 inches larger than your oven rack.
Aluminum foil
Roasting wrap (optional)
Scotch tape or duct tape
Charcoal (1 charcoal equals 40 degrees. Use 8-9 pieces of charcoal for a 350 degree oven)
12-14 pieces of charcoal will bake a cake (box mix)
Four soda or soup cans filled part way with sand (will form the base for the cooking rack)
Oven rack

The Box
Line the inside of a heavy corrugated box with aluminum foil, shiny side out, bringing the foil around the edges and down the outer side about 6 inches. Tape down. You can cover the entire box, inside and out if you wish.

If you want to watch what is happening in your oven, cut a square hole in the solid top of the oven box, and tape clear plastic roasting wrap tightly over the hole.

To Use:
1. Get your coals going. Use them only once they are completely gray. Have a few extra coals nearby to use if you should need them. You can start the coals in an old metal pie tin.
2. Put the coals (in the pie tin or not) in an even layer on top of foil laid out on the ground. Place the four soda cans filled partway with sand or dirt around the edges of the coals, far enough apart to support your cooking oven rack.
3. Place your oven rack on the top of the soda cans, over the coals. If you don't have a rack, the alternative is to push straightened hanger wires in through the sides of the box to form a rack about ten inches higher than where the coals will be.
4. Make sure that when you place the foil box over the coals, that there is room for air to get in under the box. The coals will need oxygen to burn. You can do this by slightly propping up one end of the box, digging out an air ventilation hole, or cutting some air slits on the box toward the ground. Make a few small holes in the top of your oven so that the box can draw air in from the bottom and out the top.
5. Put your cake, pizza, bread, brownies, etc. (in a cake pan or on a cookie sheet) on top of the oven rack.
6. Place the box over the rack, soda cans, and coals, again making sure the oven can "breathe".
7. Don't peek! (That's what the small hole with roasting wrap covering it is for). Wait about 30 minutes. You'll "smell" when it's done. The coals will not last more than an hour.