Most often just use the nut plate to help guide the hole location. No cost tool.
I like drilling the center hole first (#40 or #30) bit. Then use a nutplate jig to center the ears around that center hole. Catch is nutplate jigs are $45 for a new one, $10-$15 on eBay if you're lucky and snag the correct one.
I just keep a hunk of 0-1 flat stock. 0.25" x 1" is fine. Heat cherry red (1450F). Plunge in oil (there is some fancy quenching oil, but for this job nothing too fancy. I did use old motor oil, but use extreme caution as that metal is way above the flash point (common sense applies). Once quenched, toss into a 400F oven for an hour.
Yep, metal welding rod to hang it from the fuselage. Cut, drill to size, and leave to be heated up next time I'm welding something.
