The Extend NURBS menu command allows you to extend any NURBS curve or surface along a straight line or smoothed curve. To do this, select a NURBS curve or NURBS surface. Select Model > Extend NURBS
Select the end point (NURBS curve) or edge (NURBS surface) to extend by using the Next or Previous buttons. Select whether to make a linear or smooth extension. Enter the distance of the extension. Click Preview to see the result. Click OK to extend the NURBS curve or surface.
Edited by JimW