Constructing the Base

• 1). Fold the flaps of the larger box (16-by-16-inch) closed and tape shut. Place the smaller box (15-by-15-inch) on top of the flaps directly in the center. Trace the perimeter of the smaller box on the flaps and then cut the tracing out so that there is a hole exactly the size of the smaller box.
  
  
• 2). Make a mark on the smaller box at the height of the tallest pot you will be cooking with. Use a box cutter to cut the corners of the box down to this mark. Fold the now enlarged flaps at the mark.
  
  
• 3). Glue aluminum foil over all of both boxes' inside surfaces and spray-paint the exterior of the boxes black.
  
  
• 4). Put a layer of wadded up newspaper in the larger box so that when the smaller box is placed inside the tops of the boxes are flush.
  
  
• 5). Glue aluminum foil over one side of the 15-by-15-inch piece of cardboard. Spray-paint the foiled side flat black. When the paint is dry, place this piece of cardboard inside the smaller box with the foiled side up to act as a drip tray.
  
  

Constructing the Top

• 1). Place the larger box in the center of the 18-by-18-inch piece of cardboard and trace its perimeter onto the cardboard.
  
  
• 2). Use the box cutter to make diagonal cuts from the corners of the tracing to the corners of the piece of cardboard. Fold the sides down at the edges of the tracing and fold them over each other where they overlap. Tape the folds to each other where they overlap to form the lips of the top of the oven. It should look like a box lid.
  
  
• 3). Trace the perimeter of the smaller box in the center of the newly constructed lid and cut the tracing out on three sides. Fold the cutout up from the top of the lid along the still intact edge.
  
  
• 4). Stretch the oven bag over the resulting hole on the bottom side of the lid. Glue the bag to the lid and then glue the bag closed.
  
  
• 5). Cover the bottom side of the lid's flap with aluminum foil. This flap will be used to reflect sunlight into the oven.
  
  
• 6). Cut a piece of wire from the clothes hanger long enough to hold the flap open at a 45-degree angle. Make two 1-inch right angle bends at each end of the piece of wire in opposite directions, resulting in an elongated Z shape. Stick one of the bends into one of the edges of the opening in the lid and the other bend into the flap so that the wire holds the flap open at roughly 45 degrees.
  
  
• 7). Place the drip tray inside the smaller box, place the smaller inside the larger box and then glue its flaps down. Cover both boxes with the lid and the oven is ready for use.