Cutting Geometry with Nested Void Families in Revit

1. Generic Host in the Face-Based Family:
   • Within the face-based family you create the void, Cut the Generic Host
   • This setup essentially simulates the cutting action within the family editor, preparing it for similar behaviour once loaded into another family.
2. Set Up for Nesting and Loading:
   • Confirm that both the void and the host are correctly configured. For instance, make sure the void is designated to cut and that the family is set to “Cut with Voids When Loaded” if necessary.
3. Nesting and Placing the Family:
   • When this void face-based family is loaded to another family (is nested), the void should now cut through the actual geometry when an instance of the face-based family is placed.

This approach exploits Revit’s handling of generic hosts and cutting behaviours to facilitate desired outcomes with nested voids. It’s particularly useful in scenarios where direct cutting by nested voids is either not straightforward or not working due to Revit’s constraints on family behaviour and geometry interaction.