i really dont think there is a mass produced skid plate for the focus. carbon kevlar would almost be a garunteed no find. That and its so high dollar for its strength and lightweight.
Other under body protection and gas tank protection go with 1/4" LDPE.
I think its anywhere from 100-150 a sheet. it might have gone way up. havent checked the prices for a while. youll need 2 sheets for sure.
Riv nut it or weld nuts in place for fitment. no screws for sure.
not that u already havent thought about this but when u r drilling holes in the skid plate for mounting make sure the holes are chamfered a bit so the bolt heads lay flush inside so they wont get knocked off or rounded by rocks.