I apologize, I did not want to mean that is due to Pufferfish. Yes, you are right, if I try to offset that surface with rhino creates the same result, so the word should be “undesired” surface instead of “odd”, sorry about that, and I’m pretty sure that there is a consistent reason, perhaps the curvature of the surface near the edges, I don’t know.
What I’m trying to get is and offset of 1,50 mm opposite to the normal of the original one, If I offset the original untrimed surface I’m getting a polysurface that I cannot trim to get the same result as the original trimed one at a 1,5 mm distance as you can see on the attached file of my previous message.
Michael, do you know if what I suggested to Kim is possible ?
Thanks, and sorry again for my bad explanation of the issue.