Shell Solid

In this Task 

An interior wall depth will be added to the new solid by creating a wall thickness of 5.

For material to be subtracted, an inward shelling will be produced.

The top and bottom faces will be excluded.

Before you Start 

The view is set to Isometric North East.

Workplane is displayed.

Take Note 

To create a wall thickness which adds to the material (outward shelling) input a positive shell value.

To create a wall thickness which subtracts material (inward shelling) input a negative value.

Shell Solid

Ribbon : Modify | 3D Modifications | Shell Solid

Default Menu : Modify | Modify 3D Objects | Facet Editing | Shell Solid

Palette : 3D Model | 3D Modify | Shell Solid

This feature will either add or subtract wall thickness to an object by inputting either a positive or negative value.Any facet of the solid can be excluded from the Shell function.

Select the Shell Solid tool from the menu options above then input a value of -5 into the thickness field.  Select the solid object anywhere on its shape.

At the prompt > select a face to omit, place the cursor over the top face until the thick green outline is displayed, shown below.

Left click when the top face is outlined, shown above.

Use the Page Upor Page Down keys to select the bottom face of the solid, shown below. 

Left click when the bottom face is outlined in green, then right click and select Finish from the local menu.

The result should be similar to the illustration, below.

Model rendered using Draft Render mode – Visualize