Break down project into manageable chunks by creating Construction Work Area.
Work Area can be created by:
As a result Work Area object is created with a 3D elements relationship that belong to Work Area.
Recommendation is to create Work Areas before cost codes assignment as Work Areas creation might remove assignments.
Drawing custom polygon:'Work area from graphics' tool allow to draw a custom polygon, all visible elements intersecting polygon's boundaries will be sliced. As a result Work area is created with elements from defined polygon.
Tool also allows adding individual elements into Work area.
Select existing 2d design shape
Select existing 2d design shape to create Work Area with boundary of selected shape.