Modulation command, Envelope curves

 From:  bemfarmer
5592.1 
Are there any thoughts on how to modulate a curve, or constrain the curve between two envelope curves, in 2D?

It can be done with two parametric equations, by multiplying them. For example sine.

It can be done with a brute force selection of say 1000 points, with two curves, and multiplying them.

The lower curve could be different than the top envelope curve.

Maybe some way to do it, using nurbs equations?

Could be useful for Guilloche.

Did some Flow, with line segments.


EDITED: 30 Mar by BEMFARMER