O, thanks for your explanation Michael! NURBS modeling is very unusual to me. I tried to model this thing via Construct > Network, but there some "defects" like bemfarmer said. Maybe there is special method to model things like this (it's mobile router back cap)? I can do this thnig in XSI (my primary package) with poly modeling, but I want give MOI a try. I attached 3dm file with "defects", and photo of this evil object :) Many thanks for your help guys!