Henry, Thanks very much for your prompt reply! I'm in the middle of some other work, so there is no hurry about this question, but I would really like to see an example of how you incorporated a Python script into a Rhino model. The best I could manage was to use Mathematica to calculate some points on curves, output their coordinates as text, and input that text as a set of points into Rhino. That allowed me to get the curves accurately into a Rhino model. Surely you had a better way to get the quadratic surfaces you made! I greatly admire your designs!