User customizable center balanced S hooks

This is a user customizable S hook (center balanced) that you can control the following parameters for (via Fusion 360 User Parameters):

* Opening size of the top and bottom hook
* Overhang (+/- degrees) of the hook
* Diameter of the hook

Some example hook STL's are included if you are not familiar with Fusion 360. You can also use scaling in your slicer to get some other sizes.