I have made several Solar Box Cookers out of cardboard and a few other supplies for your Burning Man meals. I have posted a lot of information below that will hopefully answer your questions. Feel free to contact me with any more inquiries you many have. Am open to all trades!

*Three Reasons Solar Cooking Deserves New Attention

1. One-fourth of humanity suffers fuel scarcities. Half of the world cooks with wood. Accelerating wood shortages in many countries add new burdens to families, particularly in eastern and southern Africa.

Families must be fed every day.
Rural women of all ages - including those who are pregnant and have infants, the elderly, and very young girls who should be in school - spend more time and walk ever-longer distances to find, then carry, heavy loads of wood.
Urban families in many developing countries now spend up to a third of their income for cooking fuel.
Refugees in Kenya, prior to getting solar cookers, often barter away part of their food rations to get fuel to cook the remainder.
Many families are unable to cook nutritious foods such as beans and maize, which require hours of cooking, and substitute less nutritious, faster cooking foods such as pasta.
Families are also less able to heat/pasteurize their water and milk to reduce water borne-diseases, the major killers of children. Solar cookers easily cook most foods and pasteurize milk and water.
Fuel-gathering is one factor in the tide of migration to cities. A rural Zimbabwean summed up the possibilities: "Today many young Zimbabwe women don't want to stay in rural areas because gathering fuelwood is so difficult and time-consuming. Solar cookers can make rural life easier for women so they'll want to stay there."
The annual per capita wood consumption for cooking in most parts of the world is about .5 ton (1.32 kg per day), or about 3 tons per family of six people. A solar cooker can save one ton of wood per year.
The cost to replace cut trees in India is double the market price of cut wood.
Many governments including Zimbabwe and Kenya import and subsidize less sustainable fuels at great expense.
2. Current cooking methods are unhealthy, unsustainable and unavailable to future generations.

Cooking with fire means fire hazards and dangers of burns for small children
Smoke causes lung and eye diseases.
Future generations will have fewer options.
3. Improved solar cookers and training

Historically most solar cookers were either curved parabolic reflectors focusing intense heat onto a single pot, or heat trap boxes with a window on the top and one or several flat reflectors. Both types were too expensive for most people, cumbersome and sometimes even dangerous to use.
A wide variety of new solar cookers are more convenient, much lower-priced, and now competitive with alternatives such as wood, charcoal, and wood stoves. One such model, an open reflector, has been widely tested and has proven useful in the USA, Kenya and Zimbabwe. It pays for itself in fuel savings in two months or less and becomes a recurrent economic benefit to individual households.
Developed in 1994 by an international team of volunteers and dubbed the "CooKit," it is ideal for introducing the basics of solar cooking. It is easily hand-made and also is being mass-produced in USA, Kenya and Zimbabwe with modifications to suit local needs and climates.
Participative instruction quickly teaches solar cooking skills and trains local women to also teach their neighbors.
Many millions are waiting for the simple, life-long skill that they can pass on to future generations.

How hot do solar ovens get?

Place an oven thermometer in the sunny part of then oven to get a reading similar to what the cooking pot if "feeling". The temperature reached by box cookers and panel cookers depends primarily on the number and size of the reflectors used. A single-reflector box cooker usually tops out at around 150° C (300° F) as the food approaches being done. High temperatures, however, are not needed for cooking. Your oven will cook just fine as long as it gets up to about 90° C (200° F) or so. Higher temperatures cook larger quantities, cook faster, and allow for cooking on marginal days; However, many people prefer to cook at lower temperatures, since then they can leave the food to cook while they go about their business. With a single-reflector box cooker, once the food is cooked, it just stays warm and doesn't scorch. It's good to keep in mind that no food can go above 100° C (212° F) at sea level anyway, unless a pressurized cooking vessel is used. The high temperatures you see in cookbooks for conventional ovens are just for convenience and for special effects such as quick browning.

How long does it take to cook a meal?

As a rule of thumb, you can figure that food in a single-reflector box cooker will take about twice as long as in a conventional oven . However, since you can't really burn your food, you don't have to watch the cooker or stir any food as it cooks. You can just put in a few pots with different foods and then come back later in the day and each pot will cook to perfection and then stay hot until you take it out.

Panel cookers cook smaller portions, usually only in a single pot, but often they cook slightly faster. Some people have reported the need to stir food every once in a while when using this kind of cooker to assure that the food heats evenly.

Cooking with a parabolic cooker is very similar to cooking on one burner of a conventional stove. Since the concentrated sunlight shines directly on the bottom of a pot, the pot heats up and cooks very quickly. The food will burn though. So you have to stir it and watch it carefully.

Do you have to turn the cooker to follow the sun?

Box cookers with one back reflector don't need to be turned unless you are cooking beans which take up to 5 hours. Panel cookers need to be turned more often than box cookers, since they have side reflectors that can shade the pot. Parabolic cookers are the most difficult to keep in focus. These need to be turned every 10 to 30 minutes, depending on the focal length.

Please check out solarcookers.org.

Thanks!