Offset Surface

(3D only) Used to construct a Smart Surface by offsetting an extruded surface, surface of revolution or a B-spline surface.

You can access this tool from the following:

Setting	Description
Distance	If on, sets the offset distance in the surface normal direction.
Face Only	If on, lets you select an individual face of a surface to offset.
Keep Original	If on, the original element is retained.

Key-in: CONSTRUCT OFFSET SURFACE