I’m seeing this weird result recently… Curves are correctly oriented, points and section are in the right order yet the result is incorrect…
I have to flip the rails or revert the points for the Brep.CreateFromSweep to work correctly.
I’ll try to revert to a previous version of Rhino because I’m pretty sure I’ve tested this a few weeks ago and it worked. Maybe I was dreaming… → I was not but it was a different case :
The problem does not happen with two or more sections.
CreateFromSweepFlip.gh (9.9 KB)