Editing tools that create multipatch and 3D object feature geometry automatically snap to the geometry you are actively drawing. When you hover near a snappable 3D geometric element, an orange snap agent symbol appears with the pointer, and edge extensions appear as orange dashed lines.
Multipatch and 3D object feature snapping is described in the following table:
Global axis or line extension
Snap to the global axis or line extension.
Snap to the vertex of existing geometry.
Snap to the inferred intersection.
Constrain the new segment 90-degrees to the previous segment.
Constrain a new segment parallel to existing geometry.
Snap to the midpoint of existing geometry.