Tinfoil Ovens
Line a cardboard box with foil (wine-bottle boxes and small movers' boxes work best). Place a cookie cooling rack on 4 pop cans filled with water. Put charcoal or coals on a foil plate and light. Allow the charcoal to get hot and then place them into the oven, under the rack. Add the food you are cooking, close up the box and only open when checking on the food.
Some great ideas of stuff to cook in foil ovens include pizza, cakes, muffins, apple crisp, etc.
If you are careful with your oven and keep it clean, you can use the oven over and over again!