This is a simple spring clip. It can be easily modified in OpenSCAD. ( See below )

The design shows that even PLA can be used to create quite robust springs as long as they are long, relatively thin and printed with perimeters only.

The spool hub pictured is this one: Springy Spool Hub.  It is customizable as well.

Slicing

Slice with only perimeters like pictured on the right to create the most robust and flexible part.

Customizing in OpenSCAD

To create your own version download the free OpenSCAD application that is available for Linux, macOS and Windows.

Download the “ring-clamp.scad” file, open it, and if not already the case display the “Customizer” tab by selecting the entry in the "Window" menu.

All customizable parameters for this model are documented in the user interface.

Select “Render” and then export your generated model.

If you adapt the hub to your spool sizes make the diameter bigger than the maximum hole size you want it to fit. As a rule of thumb about 5% plus. This guarantees that the springs have enough tension to lock it in.

Happy Printing & Customizing