Click Thick Surface
in the Surface-Based Features toolbar.
The Thick Surface Definition dialog box appears.

Select the element you want to thicken, that is the
extrude element.

In the geometry area, the arrow that appears on
the extrude element indicates the first offset direction. If you need
to reverse the arrow, just click it.

Enter 10mm as the first offset value and 6mm as the
second offset value.
Click More to access
the Deviation parameters.

Select the Smoothing mode among these three types:
-
None:
No smoothing is applied. This is the default option. The Max
deviation box is unavailable.
-
Manual:
Allows you to enter a maximum deviation. The default value is 0.1
mm.
-
Automatic:
Smoothing is applied automatically.
Note:
You can select the Disable Tangency Continuity check box in the Lateral Edges area to avoid tangency continuity on the lateral edges.
Click OK.
The surface is thickened. The specification tree is updated.

Note:
The resulting feature
does not keep the color of the original surface.