The sun is arguably one of the humanity's most important tool for survival. It gives off practically unlimited amounts of light that is used by plants to generate energy and animals for heat. It can be used to generate electricity with solar panels, hot water with solar hot water heaters, and many other uses. Even though technology can be very useful, for example gas ovens, natural and simple technologies like solar ovens can reduce fossil fuel use or even replace fossil fuels in places that don't have abundant resources, and it's an enjoyable project. The materials used can mostly be found locally from recycled sources which makes it even more sustainable.
Step 1: Finding Tools and Materials
I recommend taking one trip to locate/buy tools and materials for this job. The following materials are necessary:
-2 medium to large cardboard boxes that fit inside each other with 3-4 inches or so of space around the sides of the box. Also necessary is a large piece of cardboard for the reflector that is as wide as the widest part of the large box and about 2-3 feet long. These can be found at most stores, just ask an employee for boxes they don't need anymore.
-1 roll of aluminum foil (75 feet is enough)
-a piece of glass or plastic fits over top of the larger box. This can be found at window stores; they often have extra glass laying around for free.
-black spray paint or black construction paper
-enough newspaper that will, crumpled, fill a bottom row and the sides in between the two boxes. This can be found at recycling centers.
-duct or foil tape
-two small pieces of wood (optional)
Step 2: Cutting Off Flaps of Smaller Box
Cut off the four flaps of the smaller box so they don't get in the way.
Step 3: Crumpled Paper on the Bottom
Crumple up pieces of newspaper one at a time until the bottom of the large box is lined. This will be an insulation that keeps retains heat in the box.