I honestly don't know much about them. In one of the links posted up, a lot of those looked like open air designs. I figured you'd make one like that pre-made one in the second link for $379. Something that is enclosed to trap heat in.
I did have an idea today, and don't be too hard on me if it is stupid (because it very well might be). I was thinking that if you made one that was the same curve as your windshield, you could cook small meals by setting the oven up on your dashboard. If that worked, and was safe, I'd probably bring lunch for when I'm shooting matches. Go throw a potpie into my dashboard mini oven between stages, and go check it after the next stage.
Are you being facetious? If not, I don't understand what you mean at all. I'm under the impression that cold, is merely the absence of heat; so I'm not sure how you could radiate it, or get temperatures colder than ambient. If this is possible, then I am just as interested in this, as I am a solar oven.