Here is a tool from @ottofrei1930 that is helpful when you have to stamp the inside of a ring (my example is a unfinished, cast practice ring 😄) the Brass Stamping Block will provide support and the outside of your ring will have minimal distortion. It’s Part # 155.395 at Otto Frei and our code is MMSZ now it should be mentioned that if you can, plan ahead in your design to stamp your metal when it’s flat because that is always the easiest but in instances like this cast ring the inside stamp and block works!