Thank you BurrMan and Michael for your network-tips. I had already ruled out the idea to make a larger surface and trim it, because all I could come to think of was to make a surface of revolution and then trim that, but that wouldn't have worked for those eight cornerpoints.

The important thing for the surface is really that it's smooth and that it blends together well once you start copy it. And the networksurface seems like it does both.

Thank you very much both of you, I learned a lot.

/Lars