What is a Ring Mandrel? Which One Should I Buy? - International Gem Society
Amazon.com: Expanding Ring Mandrel with Hex Allen Key – Medium Premium Stainless Steel Ring Mandrel for Lathe – Heavy Duty Ring Shaper Tool for Ring Turning and Ring Making - Ring Sizes(7.5-10.5) -
Expanding Ring Mandrel Stainless Steel (Large) | eBay