This instructable is about a solar oven I made out of an old picture frame, two cardboard boxes, some duct tape, aluminum foil, white glue and crumpled newspaper. You will need to find a picture frame. I used regular glass but tempered glass would be better as it gets very hot and could shatter if you spilled cold water on it. I think I used about a 12 x 14 frame, not sure as it was a few years ago. What ever size glass you find will decide the size of the inner box and the outter box should be 2-3 inches larger. You need to cut a hole in the larger box to fit the inside box then crumple up some newspaper and pack between them.
I have baked pies in my oven, if a bit slower than the recipe recommended.
The frame you incorporate is a good touch. Wish mine had had one. Air leakage from the glass just sitting on the cardboard top downgraded the efficiency of my design over time. A caution about the duct tape, though. It works for awhile (if away from the hot portions; the plastic melts) but eventually will fail.
Your Solar Baby designs look great. However, I'm working on a plywood and sheet aluminum version of my cardboard build since it has worked pretty well for me. I will post it when it's done.
How long it takes to cook things will depend on how hot your oven gets, but it is generally slower than cooking in a regular oven--perhaps an average of half again as long? I wouldn't use plexiglass. I have not tried it, but the glass gets hot enough to burn your fingers. There's a good chance it'd collapse onto your food, not to mention the fumes it could release.
A great project to read in a rainy, cold, overcast saturday ! LOL
Thank you all the same !…
GM