Take a car tire or black inner tube, place it on a piece of plywood. Line the hole with aluminum foil. Place a cooking (ovenproof) dish, black enamel pot, roaster, etc. in the middle of hole with the food to be cooked. Cover tire with large piece of glass. This will work on a sunny day.
By Tammy from Columbia, Missouri
Editor's Note: Here are plans for a similar design.
I've always wanted to make one of these, but there were just so many steps that I never bothered. This one is EASY, quick, with almost no assembly. I'm sure it's going to be the one I'll try. Thanks.