:agree: with the three posts above me.
Clay is only useful as a molding medium in armor making, not as a finished product. Even Super Sculpey is a bit too brittle for making armor... even if you could afford enough to make a full suit or helmet.
The techniques that we have put forth in this site have been tested, refined, and utilized by propmakers for years... You don't need to re-invent the process, just learn from the instruction we're giving you on how to make armor using the methods already presented.