A 8-blade ball style finial (rod end), designed to replace the awful finials that came with the curtain rod fitted in the house when I bought it.
As the 2 ends on the curtain rod were different sizes it wasn't much more effort to make it customizable. Rather than just make the bore configurable to has many features that can be changed.
Thanks to Lyl3 this thing seems now to be working correctly in Customizer; a degree symbol in a comment was the culprit.
If you don't want to use Customizer you can download the .scad file and edit the values in OpenSCAD.