I made and installed the wing tie downs today. Took all day. I taped the tie down with 3/8 X 16 male tap. I bought a new, higher quality die, rather than using my old cheap ones. It was easy. Then I cut the 1 inch diameter holes. I tried it first with a step down bit, but it only goes to 3/4 inch. I bought a bi-metal drill bit which claims to be good for wood and aluminum. It worked pretty good. I used a scotch bright wheel and sandpaper to smooth the drill bit marks.
