creating a para_dim=2 spline with two para_dim=1 splines

[j042]

I roughly think of something like this:

# from
*-----*-----*--*---*----* 



*-*--*-----*------*-----*

# to
*-*--*--*---*--*--*--*-*----* 
|                           |
|                           |
|                           |
*-*--*--*---*--*--*--*-*----*

[mkofler96]

This would be a reall cool feature. Many CAD applications use this a start for freeform surfaces. Usually its also possible to use multiple 1D param splines:

from https://en.m.wikipedia.org/wiki/Freeform_surface_modelling

Btw. a thickening option (perpendicular to the 2D surface) would then also be cool to create the volume 🤔