To Create a Shell Feature by Excluding Surfaces
1. Click > 
Shell. The Shell tab opens.
Shell. The Shell tab opens.2. To select the bodies from which geometry is removed, click the References tab and select an option:
◦ To shell geometry from all the bodies in the model, select All.
◦ To shell geometry from selected bodies:
1. Select Selected.
2. Click the body collector, and then select bodies from which to shell geometry.
3. To remove surfaces during the shell feature creation, click the References tab, click the Remove surfaces collector, and select one or more surfaces. You can also select one or more surfaces to remove before you enter the shell tool.
4. To modify the shell thickness, perform any of these actions:
◦ Type a value in the Thickness box on the Shell tab.
◦ Drag the thickness handle in the graphics window.
◦ Double-click the thickness value in the graphics window and type a new value.
5. To exclude surfaces from being shelled, click the Options tab, and click the Exclude surfaces collector, and select one or more surfaces to exclude from the shell.
6. To specify the surface to extend, on the Options tab, select one of the following:
◦ Extend inner surfaces—Extends the inner surfaces of the shell.
◦ Extend excluded surfaces—Extends the excluded surfaces of the shell.
7. To prevent the shell from cutting through the solid at concave corners, on the Options tab, select Concave corners.
8. To prevent the shell from cutting through the solid at convex corners, on the Options tab, select Convex corners.
9. Click 
OK.
OK.