Quote Originally Posted by NedL View Post
I make mine the same way Bethe does: a square of aluminum form a soda can ( you can cut it easily with scissors ) a sewing needle, and emery paper. I use 600 grit paper. I spin the needle with light pressure until it just pokes through, then sand on both sides a lot, then repeat. The hole is always way too small to begin with. It gets bigger as I keep working on it and with some practice you'll get an eye for when it's about right.
Yeah. The needle isn't for pushing through the foil to make a hole, it's for making a bump in the foil, and then you sand the bump off to make a hole. There are several advantages to doing it that way, including: i) the size of the hole is easier to control; ii) the hole is nice and round; iii) it has clean edges; iv) the edges of the hole are thin (this is important if you're making a hole in a thicker kind of foil, like for example a piece of beercan).

I usually use a knife sharpening stone to grind the bump down, because it's very fine grit, it's flat and it's rigid so it doesn't deform while I'm trying to make a nice precise round hole.