Can't find this asked anywhere, at all, so here goes.
Is there any way to get Ghost Touch or some equivalent to apply to natural armor? I have a character going that relies mainly on a beefy natural armor bonus, but have been struggling against incorporeal opponents. Short of making some custom item, is there any way to do this? Not worried about PFS legality, and all 3rd party stuff is welcome. Second, would turning myself ethereal allow applying natural armor?