I have a body that represents plywood planking in a boat derived from thickened complex loft surfaces. When mirroring the inner surface dissapears (the outside surface can be picked from either side as if the inner face does not exist) I have tried everything I know of but, short of rebuilding the body from mirrored surfaces and reepeating all the perforations, I cannot make it regenarate properly. I have found that the most efficient way to build a hull and deck is to make them as a multibody single part-every structural part is directly derived from the basic shape of the hull. But then mirrored bodies with complex surfaces occassionally fail in this way.