These started as thin offcuts from the scrap bin; to thin to hold on the lathe traditionally in the chuck; it would be easy to turn from the bar and part off. these required a small split bush once I had the face a back step cut.
The 16 sided polygon holds the parts for scribing; I just lightly clamp the dishes by the two M4 screws and place against an angle block. My height gauge used for scribing.