I wasn't really prepared when I proposed to my wife Kate so until I could get a real ring I made her one at work. Since I repair film & TV equipment, the band is part of an aluminum light stand and the 'jewel' is a camera bearing which spins, making it a great fidget ring. It remains one of Kate's favorite pieces of jewelry.
I tried to use the band saw, then the jigsaw, and finally a hacksaw to cut the band but none of them turned out square enough. I finally used a pipe cutter which worked great.
At this point it was pretty ugly. I drilled and tapped a hole for the bearing screw.
To smooth things out, I started with jeweler files, then moved to various fine grades of sandpaper.
The final polish was done with a felt wheel and polishing rouge. It cleaned up so well that it almost looks like silver.
Final step was to use an extremely short screw to attach the bearing. I used high-strength threadlocker on the screw so it will never come out.