The PlaneGeometryIntersection utility class computes and (optionally) renders the intersection of a geometric shape with clip plane.
In clip line mode it computes a set of line segments corresponding to the intersection.
In polygon mode it computes a set of polygon boundaries that can be used as a "cap" for clipped geometry.
The computed geometry can be rendered and/or exported (for example to an STL file).
Clip line mode and capping geometry mode.