Kyoto Box - Cardboard Oven

Detailed pic - structure

Perhaps more of a long term survival tool if the gas/juice stops flowing for a while. But I can think of a few times where building something like this out of trash or bits pulled from your wrecked vehicle could come in handy. And I gotta think that done right, it would make a good basis for a water still in a salt water or polluted water situation where boiling won't cut it.

A field-expedient version might just be too weak or hard to build. Anyone tried anything like this from scraps?

Yes, especially if you are in a sunny area.

Philip started a similar thread in the Long Term Disasters section.
You guys must have seen the same news story.

I posted a couple of links on his thread.

VITA and solarcookers.org are good sources for more information on them
They have been playing with these solar cookers a lot in the refugee camps in Africa. Wood, charcoal and other fuels are very scarce there. However the sun is free and usually more than hot enough.
Slower cooking times are fine when your fuel is the sun.

They also have some interesting articles on using solar cookers to sterilize water for drinking.
The WHO recommends heating to 156 degrees Fahreheit instead of boiling because fuel is so scarce, and have created a sort of wax filled thermometer to measure if that temperature was reached.
At 156F some of the bacterial spores survive but all active bacteria and viruses are killed. The bacterial spores that do survive are made harmless by the heat and are not able to cause infections.

I was looking at solar cookers about a year ago and have quite a few links and articles downloaded.

I have tried a couple of the designs out and they worked OK. In my experience it is better to think of slow cooking methods with them than as fast fry grills.

One other point to think about is how sunny it is where you are. The farther from the equater, the farther from high noon and the cloudier your climate is the less effective solar cooking becomes.
This can be balanced by making larger collectors to some degree.

If you are curious about parabolic reflector design cookers a man called Brian White in Victoria BC Canada has been playing with them a lot. He has been posting videos of his work on Youtube under the name Gaiatechnician.

I built a couple of these types of items back when I was a teenager; one was a reflector box using smoothed out tin foil and carboard and the other was a large parabolic reflector. The reflector box got REALLY HOT when it was pointed in the right direction, it just depends on how much reflector surface you incorporate. Not sure if I actually did cook anything with it though.

The parabolic -- well let's just say "not so much". The curve wasn't exact enough, I could put my hand at the "focal" point, it was warm but not bad enough to make me need to move the hand. It was supposed to cook hotdogs according to the book!

We made a huge cardboard box oven for our car camping trips. Only ours wasn't solar. We used a propane stove element for heating and it was great! We made brownies, cake, mochi, even a huge six hour roast in there. With a thermometer stuck in there, we could control and maintain even heating.

One thing we learned was to use a deflector so as whatever you are cooking doesn't get burned.

Total construction time was under half an hour and it lasted about eight months or roughly 30 days of camp use. We used an old broken folding chair as the oven stand. After taking the seating and arm rest panels off, we lashed the legs to fit perfectly around our box oven which was about a 24' cube.

It heated up faster than our kitchen ovens.