I don't remember the thickness of aluminum that my first one was made out of. Maybe 20 or 30 mil? But, it melted on the first burn. It didn't actually melt, more like soften and deform with the weight of the water on top. I am making a new one this week, hopefully, out of mysterious metal from work. It is a sheet that was purchased long ago, and no one knows what it is. I did some density tests on it, and think it is nickel or SS.
I've taken a vow of poverty. To annoy me, send money.