The new extrude tool

You can use the Extrude tool to create 3D solids based on existing 3D surfaces. In addition, you can edit 3D solids by drawing any outline on a surface of the solid and modeling this outline freely in three dimensions. You can even use the outline of an offset surface as the basis.

Fig.: creating a solid based on a surface

Fig.: expanding a solid using an offset outline

Fig.: cutting out an outline drawn on a surface