NURBS surface self-intersection

#1

I have a surface that I created using curves and paint effect brush.
I changed shader and everything was ok before I noticed little mistake: I
have neon tubes intersecting itselves. You can see it on a pictures
below.

Note: I’m using two identifical surfaces - neon and glass tube. One of them is thicker than another one. And glass tube is
intersecting itself.
Thank you))

https://imgur.com/KLXu4Ik
https://imgur.com/oa4eDju
https://imgur.com/hILkwIn

#2

That looks like a result of single-shape extruding. I don’t know how you would fix that, with Maya’s PFX.

Essentially, you want a “sweep2” type setup for shapes like this, similar to Maya’s Birail function. That allows you to define two rail shapes instead of just one, as with a simple extrude.