• Solar ovens focus the heat and radiation of the sun to cook nearly any food product, but work especially well for baking or cooking low-temperature dishes like grains and vegetables. Plans are widely available to help you build your own efficient solar oven. Many plans use foam in a variety of ways to improve the oven.
  
  

Insulation Board

• Strong, durable foam insulation board makes a good choice for building a lightweight solar cooker or oven, says the Solar Cookers International website. Choosing a quality foam board that is reinforced with embedded fibers ensures that your solar oven will last for years of daily use. Regular Styrofoam and polystyrene foam boards become warped and damaged from the intense heat of a solar oven and the constant sun exposure. Many of these insulation boards come prewrapped in foil, saving you the trouble of attaching foil tape or foil sheets to the foam.
  
  

Insulate and Seal

• Like all solar cookers, solar ovens must be tightly sealed and insulated to reach proper cooking temperatures. Foam board or spray foam insulation can be used on solar cookers built from wood or cardboard for extra insulation, according to Tamara Dwyer's Solar Cooking website. Foam board is easily cut by a utility knife, but care should be taken when cutting to make straight lines that will form tight seams. Apply heat-resistant silicon or a heat-tolerant foil tape to the seams to keep all of the oven's heat inside with the food.
  
  

Aluminum Tape

• If you are using plain white foam boards to create the interior of your solar oven, you may be frustrated by the difficulty of applying a smooth sheet of aluminum foil for reflectivity. For an easier aluminum application, try aluminum foil tape, recommends Cantina West. This tape is often used to repair heating ducts and other hot surfaces, so the adhesive should not melt or fail when the solar oven is in use. Aluminum tape will be more expensive than using normal sheets of foil, but it can save you hours worth of work.
  
  

Build Reflectors

• Reflectors help send more sunlight into the reflective interior of the oven, raising the temperature greatly. Reflectors also capture sunlight from different angles, reducing the need for adjusting the oven box as the sun moves, says Teach Engineering. Even if your solar oven is constructed from cardboard or wood, a foam board reflector could improve its top temperature range and cooking capabilities. Foam is a good material for building reflectors because it is lightweight enough to sit on top of an existing oven without knocking it over.