How to change Closed surface

Hi all.

I’m using Rhino V5 (5.7.31105).
I don’t know how to change closed surface to open surface.

Is it possiable?

I’m afraid you can’t, in the same way that you can’t change a closed curve to an open one by trying to open the seam.

Why do you need to do this?


Sometimes, I need to edit control points for organic architecture forms manually.
Thank you for the answer.

Well, you could Split the surface by isocurve with Shrink=Yes very near the seam line. That may give you something close enough, especially since you are going to edit it anyway…


The same question is interesting to me.