Use the extruded method to create a Shell by drawing its profile on a plane (either freehand polygon or a default shape), then extruding the profile. For example, you can extrude a Shell over the walls of a building.
See the following sections for basic creation of Extruded Shells:
Simple Extruded Vault: Parallel to the Floor Plan
Simple Extruded Vault: Perpendicular to the Floor Plan
Extruded Shell with Freely Defined Profile
For more examples, see Sample Workflows for Shell Creation.