Make an easy solar cooker. It doesn't work that well as I was only able to cook cheese and not an egg, but it is relatively fun and easy to make. You are probably better off buying a solar cooker.
Materials: Pizza box, black construction paper, duct tape, plastic wrap, aluminum foil, razor, and any acessories that float your boat
1. Take the pizza box and cut out a square section like I have.
2. Peel back the flap that you have made and put tin foil on it to reflect light into the box.
3. Put black construction paper on the inside to absorb light.
4. Put whatever food you want to cook into the box(make sure that it is something light) as it can only cook lighter food items.
5. Put plastic wrap over the top of the oven and duct tape it in place.
6. Duct tape the rest of the openings in the box as much as possible to create an air tight seal and trap in the heat.