Parametric Insert for Ringbending Pliers

Ring bending pliers are quite a useful tool when it comes to bending material in order to form proper rings - especially when the material is a bit thicker.
The ring bending pliers I have came with one (steel) insert. I wanted additional inserts to suit different ring sizes. The inserts can be modified to fit different makes of ringbending pliers (the default values are taken from the steel insert that came with my pliers).
Ring sizes (outer diameter of the ring bending plier insert) for the inserts can be specified as (inner) ring diameter or circumference.