SketchUp for Woodworking - Google SketchUp Workshop: Modeling, Visualizing, and Illustrating - page 139

FiG 8.5 Create the arch.
FiG 8.6 Preparation for intersecting the cove with cut-out tools.
Explode all components (Cove molding and Cut-out tools); select all,
right-click on the selection, and choose the option Intersect Selected from the
pop-up menu. Use the Eraser tool to clean up the waste, and see the results as
shown in Figure 8.7.
Now, we are ready to assemble all the components into the completed
cornice assembly as shown in Figure 8.8.