This isn't working as I think it ought to. I've created a surface that's the side of a kayak hull. I've extruded the surface, linked-mirrored the extruded solid across the centreline, and intersected the two solids. I've used linked-mirror because I want an edit of the surface or its generating profiles to propagate to the other side of the solid. Using the concept explorer, I can edit the surface by deleting one of the generating splines, for example. But, when I try the same operation through the concept explorer on the child solid, it gives a "can't do that" message "intersection vertex with bad or no attributes:intersection (object ID)" and degenerates the solid. If it's an intersection product of an option mirror instead of a linked-mirror solid, it'll remove the curve, but the change is only propagated through the initial surface and the extrusion solid, not its mirror ie one side only. Created in VC 7, but I've tried it in FX 8 with the same result. How much associativity is too much? I think it ought to work through the linked mirror.