What you’ll need:
One ‘oven’ box square or rectangular (minimum dimensions: 12”L x 12”W by 10” Deep) painted black inside to absorb more heat
One ‘insulation’ box (3” larger on all sides than oven box)
Several pieces of cardboard to fit between oven box and insulation box
Four pieces of cardboard measuring at least 4’x4’ for reflector panels
One small roll of heavy duty aluminum foil
One piece of scrap glass about an inch larger than the area of the oven box.
Some electric and scotch tape, string, a box cutter, ruler, marker and a thermometer that can measure temp. up to 400 degrees Fahrenheit
Five Easy Steps: This solar cooker is from Joe Radabaugh’s book: Heaven’s Flame
1. Fill insulation box with enough neatly cut cardboard so the oven box nests snuggly inside just an inch below the top. Your piece of glass should rest on top of the oven box evenly; so there is no loss of heat to outside air.
2. Take a piece of 8½x11 paper and fold it to make a 45 deg. angle. Fold the folded piece back on itself making ½ - 45 deg angle = 22.5 deg. With that piece folded, unfold the first fold and now you have a 67.5 deg angle (45+22.5), the ideal angle for reflectors. Now that’s practical geometry.
3. Your reflector should look like this:
If you have a square they’ll be identicalA rectangle 2+2
4. Tape the aluminum foil on top of the reflectors. Cut holes in the flaps and use the string to tie them together (its ok if they’re loose).
5. Set your DIY solar oven in the sun, propped up at an angle so that there isn’t a shadow cast in the oven box. Place water to heat or food to be cooked in glass (mason jars or 1 gal jugs are great) or pots painted black. You can also use baking pans or coffee cans for baked goods. On a sunny day, your oven should reach 300 degrees in about 1-2 hours and hold that temperature or higher as long as it follows the path of the sun.