Abstract: Unfired ceramic bodies which are to be joined together, are separately fired to the point of optimum density. The surfaces to be joined are machined to remove surface irregularities, lapped and polished. At least one of the two surfaces is machined to provide a desired cavity configuration. The polished surfaces are then juxtaposed and fired to the maturing temperature of the ceramic involved. A weight may be used to maintain the desired juxtapositioning. The outer surfaces of the now integral ceramic body are then machined to desired dimensions.