But geometry comes into play here, as that would mean the bottom of the box itself would not provide a level cooking surface. That problem is overcome by placing a metal plate on the bottom so it is level when the box is tilted up. Then the sun can shine directly into the box, so reflectors are not needed. Preparing to melt wax. The inside back of the solar oven is then automatically set for a reverse angle of 130 degrees, so it reflects solar heat directly to the cooking containers.
Wood is a good insulator, and if covered with thin sheet metal makes a very sturdy unit.
Miles made his oven portable with wheels from a discarded child's wagon. Note the thermometer in the top left corner of the frame. Then a piece of Plexiglass was cut to fit, laid on the molding, and another round of molding fitted with small screws, then another piece of Plexiglass, then another round of molding. I put a grab handle in the center of the back of the lid, just to make it easier to maneuver. Because the solar oven and the prop are secured with hinges, it can be stored when not in use in the down, or flat, position.