Freestyle > Adding Detail to the Control Mesh > Slicing Mesh Elements > Example: Slicing Mesh Elements Using a Plane
  
Example: Slicing Mesh Elements Using a Plane
The Original Shape
The Extruded Shape
Slicing a shape using a plane to create two shapes.
Slicing a shape using a plane to create more than two shapes.
Slicing a symmetrically mirrored shape.