Parametric fresnel lens (Failed)

Still decided to upload when it's total failure.
For easier modeling and printing without support to get a flat surface, took a special case for lens when R2=infinitive.
Ref: http://www.livephysics.com/tools/optics-tools/focal-length-thin-lens/

As no proper condition implemented, model fails when tuning parameter outside a certain range. Changing fold numbers will need to hand-retrace the outline and redo the revolve action.

If anyone have suggestions or tutorial on how to do parametric