Thanks for checking out this Instructable.
First I need to give credit where credit is due. I might add this cooker design is by no means my invention and is not a new theory.
Professor Steven E Jones of BYU I think originally designed and tested the model. Follow the link to his page and read how he did it.http://solarcooking.org/plans/funnel.htm
I decided to post my version and my results here as, just one more way to work with this existing design.
Okay let's get started!
First off hunt for a cardboard box anywhere from aprox 30" tall with bottom and top unassembled.
You will be looking for aprox a 2:1 ratio in size. I.E. 60" wide by 30" tall, twice as wide as tall if that helps.
I happened to have some black duct tape on hand so that ended up being what I used. It has no significant purpose other than it was available.
I also had one piece of vertical blind that had broken off at the top, so I decided to recycle it by using it as support members along fold lines. This is not really needed but I like a good durable unit when I finish a project. ( I PLAN ON USING IT)!
Next I taped all the box corner/fold seams both front and back. This gives a nice surface to work with. Let me make a note here****
USE THE 2:1 ratio for size. If you box is other than that cut it to fit aproximately . It doesen't have to be perfect. An inch or two longer would be better than shorter of course.
I used a box that was too long and you will see later where I just folded one side back and used it for added strength. You can do this if you wish but trust me depending on the thickness of your cardboard you could be having to work to hard to keep the shape you want in the finished product.
You will notice is taped the support pieces to the cardboard box. DO NOT TAPE THEM OVER A BOX JOINT **** if you do folding up and storing it later on will be very hard to do. I taped them on next to the folds and often over lapped the tape with the tape at the joint itself.