What you will need:

  • Empty pizza box
  • Ruler
  • Box knife
  • Pencil
  • Ziploc® baggie (gallon size)
  • Scissors
  • Clear packing tape
  • Black plastic (garbage bag or other similar plastic)
  • Glue stick
  • Reflective poster board (found at Hobby Lobby –Strathmore chrome – silver)
  • Graham crackers
  • Mini marshmallows
  • Chocolate
  • Bright sunny day
  • Adult supervision


  1. Eat the pizza!
  2. Make sure that the pizza box is clean.
  3. Measure your gallon size Ziploc bag and mark the top of your pizza box so that you can cut a flap slightly smaller than the Ziploc bag.
  4. Mark your box making sure that the opening will be centered.  Carefully cut the front edge and both sides.  MAKE SURE THAT YOU DO NOT CUT THE BACK EDGE as this will end up acting as a hinge for the top flap.
  5. Use your scissors to carefully cut the Ziploc bag in two pieces.  You will want to use the half that does not have any printing on it.  Cut the “Zipper” off of the top edge, then cut down the seams on both sides and along the bottom edge.
  6. Open your box and tape the Ziploc bag to the inside of the box lid covering the opening, or flap, that you just made (step #4) using clear packing tape.
  7. Line the inside of your pizza box with black plastic using glue sticks.
  8. Cut a strip of your reflective poster board the same width as the height of your flap on top of your pizza box. 
  9. Measure the reflective poster board and mark it so that you can glue it onto the flap making sure that it is centered, leaving the same amount of overhang on each side.
  10. I found that if you cut off the edges of the overhanging flaps as shown, it will keep them from catching on the box when you open it each time.  Cut flaps as shown.
  11. Measure the distance from the (side) edge of your flap to the edge of your pizza box.  Use this measurement to mark your poster board as shown, adding ½”.  Fold your poster board on this line as shown.  This will provide a way to lock your flap open when in use.
  12. Cut about 2” of ribbon, fold it in half and glue it to the bottom side of your top flap along the front edge as shown.
  13. Glue your poster board onto your flap as shown using glue sticks.

Cooking your S’mores

  1. Place your graham crackers inside the pizza box oven, directly on the black plastic. 
  2. Add a layer of mini marshmallows to half of your graham crackers
  3. Cover the other half of the graham crackers with your favorite chocolate bars or mini chocolate candies.
  4. Close the lid.
  5. Open the flap and insert the poster board side flaps into the slits on the side of your pizza box where the lid is inserted.  This will hold your flap open.
  6. Place box in a bright sunny spot facing the sun making sure that the sunlight is reflecting off of your poster board and down through the Ziploc bag onto the black plastic and all of your goodies.
  7. Now comes the hard part……waiting.  Depending on how hot of a day it is and the intensity of the sunlight, this can take up to an hour for the marshmallows to melt.
  8. Once your chocolate and marshmallows are sufficiently melted or, you just can’t wait any longer, carefully close the top flap and open your box to retrieve your S’mores. 


My Pizza box oven was running at about 165 degrees and I used mini candy bars that contained caramel

(ie; Rolo’s and snickers) and the caramel will hold the heat and become VERY HOT. 

Use caution and make sure that you do not burn yourself.

What is going on?

Your pizza box oven is commonly referred to as a solar cooker which converts sunlight into heat energy.  As the sunlight is reflected into your pizza box it is absorbed by the black plastic lining.  As this plastic heats up, it in turn heats up the air that is contained inside your pizza box, which then heats up your goodies causing them to melt.

Try this:

If you do not have any of the reflective poster board, you can use aluminum foil as your reflector but you will need to add a pencil or dowel to the side of your flap to hold it open. 

You could try different types of black plastics for the liner to see if one will absorb more sunlight and produce more heat.

You could also try using different clear plastics on the box top to see if one will allow more rays through it to create more heat.

Whatever you try, you must try different types of chocolates such as mini candy bars to create various flavors of S’mores!  I did find that the mini marshmallows seemed to work much better as they melted a lot more evenly and didn’t take as long to get hot all the way through to the center of the marshmallow.

Radical Rick

Extreme Science



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