Cooking in foil (besides wrapping and baking or grilling) is pretty awkward at best (try fixing hobo stew in a foil-formed pot). It's kind of like the idea of a solar still for water... looks good on paper, but real world experience just doesn't support it. For those who insist that it's THE way to go, good luck, but for myself, I'd just as soon have a dedicated SOLID cook pot (let's face it, a canteen cup or small trail pot weighs next to nothing and doesn't take up a lot of space).

Troy