This tool can be used to hammer on curved surfaces like rings etc. I am not sure about the name of this tool. Cobbler’s use a somewhat similar tool which they call the cobbler’s last. Message me the correct name (email at regainartntools at gmail dot com) of this tool and if you right you will win a 10% discount coupon.
please see the images for size etc. The maximum diameter that you can work on is 0.9 cm. The tool alone is 80 grams. The wooden base is about 200 grams. It can be ordered alone or with the wooden base.