Right, well, we all know that holes (from injury or disease) in a living human’s skull can be surgically repaired with a metal plate attached over the bone, and I’ve even seen a kid who had over half his skull replaced with acrylic after a gunshot wound destroyed it (and the brain beneath).
My question is: how much of the skull, at maximum, could we replace with current medical technology, without killing the patient (whom I’d judge has been through enough already)? How much has been replaced in a single person? Could you replace the entire cranial vault?