If you plan on making rings, you need to get a ring mandrel.
JDG Pro Ring Mandrel, Projects
The Ultimate Set includes all four highest-quality, stainless steel Expanding Ring Mandrels and a hex key. It serves the full range of common ring
Expanding Ring Mandrels - Ultimate 4 Set
This Attractive And Useful Mandrell Goes From Workbench To Showroom Without A Second Thought. Highly Polished And Professional Looking Hardened Steel
Solid Steel Ring Mandrel Sizes 1-15 - TJ01-19712-86
PrecisionFit™ Steel Marked Ring Mandrel (USA Sizes 1 - 16)
Steel RING MANDREL W/MARKINGS (sizes) - Metal Designz
Ring Mandrel Steel A-Z+6
PrecisionFit™ Aluminium Marked Ring Mandrel (USA Size 1-16)
Ring Sizer Measuring Tool Set Including Ring Mandrel Metal Ring
Ring Mandrel – uptowntools
Aluminum Short Ring Mandrel 6.25 in Length - JSKIT00066
PrecisionFit™ Steel Marked Ring Mandrel (USA Sizes 1 - 16)