I have the KM Precision shell holder I use for neck turning and manual case prep. But when I purchased it they didn't offer a hand grip ring and a wrench or tool had to be uses to tighten. They now sell an aluminum ring for $24 plus shipping.

Made this print so its tool free to use.

Print and pin in place with a 3mm rod. You might need to run a drill bit through to clean it up. I also recommend putting a 2-3 degree bend in the middle of the pin for friction fit.