I noticed that the Sun Flair portable solar oven I bought for the boat was made from reflective, Mylar coated insulation/bubble wrap. There’s a picture of one above. So when it came to my design, right away I went to the cheap, folding windshield suncover; it’s the same stuff. So that’s where I started and that’s where you need to start. Everything else you buy/fabricate will be based on the size of suncover you start with.
They come in all sizes, but I bought the largest I could find (to maximize insolation). As you can see from the photo, mine was about 30″ tall so I based all of my dimensions of this height. You will also find that the windshield suncover can [usually] be cut in half to make two ovens. Not knowing which design would work out best I made two designs from the same suncover; one similar to the Sun Flair design (flat-sided) and one based on a parabolic reflector.
Whatever size you buy, the drawings provided [in following steps] are based on the height of the suncover, so you should be able to fabricate one from any size you buy. Note, I can tell you that the amount of BTU’s that your oven will generate is based on the opening size, so the bigger the suncover the hotter the oven.
So, first you will need a windshield suncover. I bought my 30″ tall cover from a street vendor; cost $5 [new].
The second thing you’ll need is a clear cover for the front of the oven. This is probably the most important component of your solar oven. For this I recommend a good, used clear blanket/duvet case. (These are the cases that new blankets/duvet covers are sold it at places like Walmart, Target, etc.) I like using them because [most] of them have a wire along the periphery so I didn’t have to make a frame for it. You can also make it out of a clear piece of acetate, or from a good, used garment storage bag. If you look at the oval wireframe in the pictures above you’ll see I used it as a pattern for a clear cover made from a garment bag. (Keep in mind that none of the materials used in the construction of this oven have to be able to withstand any high temperatures; the only thing that get’s really hot is the cookware inside the oven).
I stole one of my wife’s duvet cover case so it was free.
You will need to get some stiff fencing wire from the local hardware store. You will make the frame opening from this. As you will see later on I made two shapes from this wire. You’ll need about 5 ft for each shape. I don’t know the cost of 10 ft, but I bought a 25′ long roll [many moons ago] for about $7.
I used a combination of Binder clips and adhesive-backed velcro to hold my clear covers on to the flanges of the solar oven. You’ll see why later on.
You’ll need about a dozen Binder clips; you can get a 100 various sizes from Amazon for $9, or you can do like I did and steal them from your wife’s desk. Cost: $0. Or, you can use a 10′ roll adhesive-backed velcro to hold things together; cost: $6. If you have access to a sewing machine, that would be a good thing. Later on you’ll see the advantage of each.
You will need some cookware. I found a used set at Goodwill for $3. The only ones I could find where actually too nice; they were stainless steel. However, you’ll want aluminum ones if you can find them. Aluminum can be scuffed up and painted with a good, long lasting coat. SS does not lend itself to a good painting surface. If you can find a good, used set of camping cookware (especially painted blank!) then jump on it! Oh yes, make sure your cookware has lids.
Aluminum Cookware: $3-$5 at the local thrift store.
(If you can’t find aluminum cookware that is already painted in a dark, matt color then you’ll have to chase up some flat black enamel spray paint. Preferably some of the ‘High Heat’ spray paint. Keep in mind that you’re cookware will not get as hot a boiling water, so ‘high heat’ paint is not a necessity, but it doesn’t hurt.)
Flat black enamel spray paint: $4/can.
One last thing; you’ll need to stitch or staple the shape(s) together. I don’t have access to a sewing machine so I stapled one of mine together and [like the Sun Flair] I used adhesive-backed velcro on the other. I did not add in the cost of the staples. (But if you have access to a sewing machine that would be good.)
$5; Car/truck windshield suncover.
$0-$3; Clear cover for the opening
$2-$4; Fencing wire
$1-$2; Binder clips and/or adhesive-backed velcro; $6 (access to a sewing machine would be nice too!)
$3-$5; Aluminum cookware
$4; flat black spray paint
Total (max): $15-$20 (may be more if you’re starting from scratch and an empty workshop)