Use this Function to remove the selected faces to produce hollowed out solids
HRESULT CreateHollow(ISet *pface,double offsetDistance,CString hollowName,IHollow **phollow);
face
Set of Faces to be opened by this Operation.
offsetDistance
Offset distance of the Hollow.
hollowName
Name of the hollow feature
Output Parameters
The created Hollow object.
Description
This function creates a Hollow of the Active Design. The given set of faces are used as the reference for the Hollow operation and a hollow solid with the given offset will be created. If the objectSet is empty(i.e.. it contains No faces), an internal void is created by the Hollow.