Hi Pilou, actually a Coons surface is one that is bounded on 4 sides by curves, which is different from the one I show there - that has 4 profiles in one direction and then bounded on the sides by 2 curves, so actually 6 curves involved. That does not fit with a Coons surface. (EDIT: I guess you mean splitting things up and making 3 Coons surfaces? You will probably see some effect of the splitting though instead of it being one continuous shape).

> Don't forget that SU is just a "box modeler" pushing to
> limit to "subdivision" and now "surfacing" by scripters :)

Yes, since SketchUp only works in polygons, it makes it a difficult fit for some of these kinds of tools.

Generating polygons as the output can cause several kinds of difficulties, like how accurate is the result? To get an accurate result could mean making a really large number of little polygons...

Or things like if you sweep another surface to the side of that with 1 rail in common, is it possible for the second one to have a different number of polygons in it than the first one? If so then there will not be a way to join those 2 pieces, there will be little cracks where the polygons do not match up, stuff like that.

- Michael