Hi Alex, a single untrimmed NURBS surface is defined by a rectangular grid of control points, so it's inherently a 4 sided thing. You can have some of the sides compressed down to a single point but you can't have more than 4 sides, and you have 8 sides here so that's the problem. So it's just not possible to make that shape out of one single untrimmed surface, to have it as a single surface you would need to have some trims on it.

For doing it with Network you'd need to break it up into multiple 4 sided areas.

- Michael