To create a shell solid from a planar object:
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 planar objects, the Inside/Outside setting determines on which side of the plane the shell solid will be extended; the direction depends on several factors related to the object’s creation, geometry, and placement in the document.
Click the planar object to thicken. To select multiple objects, 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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