This fire can be used for baking, though it is not as efficient as a reflector oven (which is has a metallic reflecting surface and often surrounds the item. The fire itself can be of any other form, and is placed in front of the reflector. The item to be baked is placed between the reflector and the fire. This fire is also good for getting oneself warm. The reflector can also be a large rock. If you sit (or sleep) between the reflector and the fire, the side of you facing the fire will be warmed directly, while the reflector throws heat to the opposite side. Very toasty.
If making the reflector from logs, the vertical members should be driven deeply into the ground to support the weight of the horizontal members. You can also use rocks to support them.
