An Effective Reflector Oven (for a fire)

          My troop used to have this great reflector oven, that was good for making brownies, cookies, cakes, etc. But somehow, it has been stolen/lost/misplaced/destroyed, and we no longer have it anymore. After looking at the internet for a while, I haven't found any good how to's for making a reflector oven, so maybe one of you engineers who loves camping and good food could make an 'ible on how to make a Reflector Oven. Thanks!

-Pandadude aka some dude with a name.