Does the pic of the skull model remind you of anything...? maybe something I posted a while ago?
I implanted plenty of skull implants made out of polymethyl methacrylate which is actually plexiglas (R). We use a green colored one with enriched with a antibiotic component. the product name is Palacos btw.
Another thing we do is implanting pseudoceramic implants made out of Bioverit and manufactured by this guys here:
http://www.3di.de/_englisch/about/index.htm
By sure to drop me a line whenever you gotta problem with your skull- I'll fix it for you.
Regards,
Benjamin