How to Make a Solar Cooker with Two Boxes

Solar cookers from the 1970s featured a pane of glass to admit sunlight and retain heat. Today's versions take advantage of the heat-retaining characteristics of oven roasting bags to reduce weight and avoid breakage. With two cardboard boxes and some flat cardboard sheets, glue, aluminum foil, black paint and an oven bag, you have the basic components of an environmentally friendly and very useful cooking device. After some experimentation, you may modify it to suit your individual requirements.

Things You'll Need

  • Cardboard box at least 15-inches-wide-by-15-inches-long
  • Cardboard box with flaps 1/2-inch or more wider and longer than the first
  • Marker
  • Utility knife
  • Roll of heavy-duty aluminum foil
  • 8 ounces of white household glue
  • Crumpled newspaper
  • Sheets of cardboard
  • Can of flat-black spray paint, non-toxic when dry
  • Turkey-size oven roasting bag.
  • 12-inch piece of coat hanger wire
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Instructions

    • 1

      Fold the flaps closed on the larger box. Place the smaller box on top of it. Use the marker to trace the outline of the smaller box onto the larger box's flaps. Remove the smaller box. Use the utility knife to cut along this line. Set the cutout to the side.

    • 2

      Modify the smaller inner box to be about 1 inch shorter than the larger outer box. Cut a slit in each corner of the inner box with the utility knife to the right height. Draw a line with the marker between the slits for a folding line. Fold the excess cardboard flaps between the slits to the outside.

    • 3

      Attach aluminum foil to the insides of both boxes with the white household glue. Glue foil to the inner surfaces of the outer box's small flaps, then glue the flaps together.

    • 4

      Line the outer box with wadded-up crumpled newspaper for insulation. Add enough to the bottom to raise the inner box's flaps so they just contact the flaps of the outer one. The smaller box should just fit inside the hole you cut in the larger box's lid flaps. Glue the flaps of the inner and outer boxes together.

    • 5

      Cut a drip pan that will fit the bottom of the smaller inner box using the utility knife and a sheet of cardboard. Glue aluminum foil to one side of it and spraypaint it black. Allow it to dry, then place it inside the inner box.

    • 6

      Lay a large sheet of cardboard on top of the outer box and mark a piece that's about 2 or 3 inches longer and wider than the box. Cut around the mark with the utility knife. Cut the edges and bend the sides and ends down to form a lip on all four sides. Glue the side lips to the end lips. Don't glue the lid to the box. It's removable for putting in and taking out cooking pots.

    • 7

      Draw a rectangle on the lid the same size and shape as the inner box. Cut along both sides and one edge of the rectangle. The fourth remains uncut and forms the reflector flap. Glue aluminum foil to the inside of this. Turn the lid upside down and glue the plastic oven bag over the hole created when the reflector flap was cut. Glue the open end of the bag closed. Bend the coat hanger wire as a prop to hold the reflector in place.