My method was to save-as the orignal PCB, use that to mark up the correct cutouts etc on a drawing layer, start deleting all the components and traces once done
Then exported the front panel as a VRML, and added that to the first project as a 3D model for a random part, so every time I updated and re-exported, it updated on the original project 3D viewer,
As I don't use other 3D tools, it was a quick way to make sure everything lined up.