To create a shell solid from a NURBS surface:
Click Shell Solid from the 3D Modeling tool set, and then click Preferences on the Tool bar.
Enter your shell preferences as described in Shell from a Solid Object, and click OK.
For NURBS surfaces, the Inside setting extends the shell solid in the opposite direction from the surface’s normal, and the Outside setting extends the shell solid in the direction of the surface’s normal.
Click the NURBS surface to thicken. To select multiple surfaces, hold the Shift key while selecting.
Press Enter or click the check mark button on the Tool bar to create the shell.
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