Boss adds material only to the outside of
a material volume that it intersects with in the same body.
To create a boss, there must be a closed
profile, consisting of either wireframe or sketching
curves, that defines the area to which the boss is applied. A boss can be
either solid or shelled.
By default, the profile is extruded normal to the
sketch plane. If you want to specify another
direction, specify a geometrical element to be used as the new reference.