Extrude Normal
This function returns an object with the surfaces resulting of extruding the input surfaces according to their local normal vectors plus the side surfaces to obtain a volume together the original surfaces.
The next figure shows and example of the resulting surfaces when this function is applied to four plane with hole surfaces.

Figure 1. Generation of a closed object with the extrudeNormal command.
The first parameter is the extrusion distance that may be positive or negative.
The second parameter is the mode to close the result object.
- None: Only the parallel layer is returned.
- All: Connects all edges of the surfaces. If the surfaces are connected it generates duplicate surfaces on the outer edges.
- Inner: Only connects the inner edges (holes) of the surfaces.
- Outer: Only connects the outer edges (bounds) of the surfaces.
- Auto: Study the topology and connect the naked edges. It is not recommended to use on curved surfaces with long extrusion distances because the parallel layer may not be well connected.