Twisting Plane Rig based on Circles used as rails with formulas

Check out this cool post.  Thanks to Marcello and Jay Zallan for this workflow:

One of the questions was how to correctly model a twisting element

The breakthrough: Circles.
"Let things ride on the rails"..
 

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Fear and Loathing In a CAD vs. BIM World: Perception, Breakthrough, Success & Help