This allows you to generate yarn bobbins for most spinning wheels and eSpinners.  Included are some stl files for a few types of spinning wheels, but there are also Fusion 360 Files that allow you to change parameters and generate bobbins for many more types of spinning wheels.  One trick is Fusion 360 doesn't like 0 length lines so if you don't want a feature just make it really small like 0.01mm and it will effectively disappear.

Here is a diagram showing what all the parameters you need to change refer to.

Here is an example of the parameters I used to generate the EEW Nano Bobbins.

Here is a video I made giving an overview of how all this works.

If you aren't familiar with Fusion 360 look up some instructions on changing parameters and then instruction on how to export stl files for 3D printing and you will learn the steps needed to make custom bobbins.