Folding Parabolic Solar Cooker

I remember building my first solar oven when I was like 8 years old. It was pretty cool, in my eyes. It was just a cardboard box lined with mylar with a saran wrap cover. Just barely fit a cookie tray in it. It obviously worked best at noon when the sun was straight above us, since the walls of the box were straight. This design doesn't have that problem! It's meant to mimic a parabolic shape, the kind of shape satellite dishes are. This design catchs and focuses light pretty efficiently. The main difference between this design and others is that this folds up for portability! It was made from a cardboard box. Besides that all you need to build it is the mylar, some tape, and some string. You have to cut and fold it correctly first, of course. This is a really simple and cheap design that anyone could build half decently. Ours could be a little better, but I'll probably make more in the future. I'm not sure exactly where I found this design, but here's a site with the same one: http://www.angelfire.com/80s/shobhapardeshi/twelvesided.html. There are lots of other designs out there, some made from umbrellas!

It still needs some kind of stand to allow me to angle it toward the sun. Apparently a bucket works well but those aren't super portable. Even sitting like this mid day, it puts out quite a bit of heat. The main thing it's still missing is a stand to hold food. I'll need to build something light that can break down, but something strong enough to hold a pot full of water without it breaking and falling on the cooker and ruining it. That's a huge flaw with this design, is that if it gets wet, the cardboard can deteriorate and the whole thing falls apart. A solution to this could be to waterproof the cardboard with some kind of spray or lacquer after cutting but before applying the mylar. Another better solution would just be to make it out of something better than cardboard, somehow. Another thing that might help with this design is a saran wrap cover to trap some heat in there, but that could lead to melting the mylar or saran wrap. Also, you can see in the picture above that some of the mylar in the center is coming loose, which  happens from folding it up and breaking the tape holding the mylar on. A better design might use spray adhesive over the whole surface.

 It folds up pretty well! Could fit between your back and backpack, or on a framepack.