There is so much more to it than that! Unless you want to hire a ceramic engineer, I'd suggest just buying the plate. Or, search the archives of the American Ceramic Society Bulletin for lots of articles on the subject (but you have to be a member - or go old school if you have access to a...
I'm looking to buy high K (>5000) X7R powder, to press tubular capacitors. The best I've been able to find has K of less than 4000. Does anyone know of a source?