Adventist Youth Honors Answer Book/Camping/Reflector oven baking
A reflector oven is as simple as a cardboard box lined on the inside with aluminum foil. Run wire through the box to create an oven rack. Make sure the rack is horizontal when the box is placed on its side. Put the box next to a bed of hot coals with the opening facing the heat, but not so near as to ignite the box. Put whatever you wish to bake on the rack. Heat from the coals will bake whatever you put inside the box. There are countless variations on this theme, including the practice of completely removing one side of the box and tilting it at a 45° angle. You can prop the box up with rocks or logs, or build legs into it.
You can also construct an oven out of sheet metal, aluminum flashing, or large tin cans as shown below. This tin can oven was constructed by a Pathfinder leader, and tested by Pathfinders in the field.