Working with NURBS Models
 
 
 

When you work with NURBS models, usually you create one NURBS object as the “starter” object, then edit the starter object or add additional sub-objects.

Here is the two-step process in more detail:

Going immediately to the Modify panel avoids the problem of creating additional top-level NURBS objects, which you can't use to build relational, dependent sub-objects. (The exception is using curves for loft and sweep surfaces. See U Loft Surface, UV Loft Surface, 1-Rail Sweep Surface, or 2-Rail Sweep Surface.)

Two general references for modeling with NURBS are Curves and Surfaces for Computer-Aided Geometric Design: A Practical Guide by Gerald Farin (Academic Press, fourth edition 1996) and Interactive Curves and Surfaces: A Multimedia Tutorial on Computer Aided Graphic Design by Alyn Rockwood and Peter Chambers (Morgan Kaufman Publishers, 1996).