Customizable Step Pulley (Inches)

This started out as a fix to thing:2105020, but I ended up having to fix all but 3 lines of code. So I rewrote those, too. (I still give credit where it is due, machineree for the concept and starting point). This module allows you to render a single or multi-step pulley.

To print a single pulley, simply leave pulley 2-6 as 0 diameter.
The module currently only supports Inches, because I am trying to see how to make that flexible in the customizer.
If you do something in the settings to cause an error, a "big red flag" will be renders in the STL, with text to explain what needs to be corrected.

Please let me know if you have questions, suggestions, or issues. This is my first customizable!