Here's a segment where he demonstrates solar cooking.

https://www.youtube.com/watch?v=AoRR_6cjmkA

It looks like it's something that could readily be made out of scrap, though, so there's no harm trying - plus it means I get to spend Monday nosing about my favourite scrapyards ;-)

Edit: from the website of one of the suppliers linked on their site, "People won’t understand why its so damn hot inside but cool to touch outside... Nothing we do is without risk and our tubes are one of the most efficient means of converting sunlight into useful heat. You accept that experimentation with the tube must always be approached with due care and diligence. You re welcome to contact us about any wacky ideas you might have, but ultimately you are responsible for your own health and safety."

"Nothing we do is without risk", eh? Now you're talking my language.