Testing of aluminum foil for leaks: I just obtained a roll of "Super Strength Reynolds Wrap". It is by far the thickest (and most expensive) aluminum foil I could find anywhere in the nation (at 34.798 microns) and substantially thicker than the thickness Wikipedia indicates is "impermeable to water” (25 microns).
My first test was to see if, when new and then shaped in the form of cups or bowls of various sizes and configs and with as few winkles and creases as is possible, this aluminum foil would hold water without leaking at room temperature. As soon as I placed water in the first test cup, it started leaking, and in numerous places. Additionally, I could see small drops of water forming on the bottom and sides of the cup in “dozens” of places other than where the main current was originating, and in many cases, where I could not see any creases and wrinkles at all.
I then flow tested the other cups and bowls I had shaped, taking as much care as possible to minimize wrinkles and creases. Each time the cups and bowls leaked all over the place. In each test cup and bowl, the water would commence flowing in some place or other immediately after placing water in them. I could also see on the bottom and sides of the test cups and bowls dozens of other places where drops were forming like perspiration, independently of each other.
My conclusions:
1) If the thickest aluminum foil that I could find anywhere leaks practically straight “out of the box” every time I tested it (while using extreme care to minimize creases, wrinkles and folds), there's no point in attempting to test whether it can be shaped such that water can be boiled in it without it leaking.
2) If you intend to use super strength aluminum foil to fashion a mug to drink beer with, you best be ready to guzzle it down mighty fast.
3) On the positive side, when grilling with it there’s no need to pre-punch holes to allow juices to drip through because it comes right from the factory with all the holes one would ever need and at no extra cost.