Abstract: A method for low cost mass production of isostatically pressed powder calm discs by placing a multiplicity of molds with powdered calcium thereon in a mother bag that is later sealed and pressed isostatically to press the calcium powder relative to its respective mold.

Abstract: A waveguide structure is fabricated by plating a mandrel with a high electrical conductivity metal, such as copper; plasma spray coating the plated mandrel with a selected waveguide body material; forming coupling flanges about the plated mandrel at the ends of the plasma spray formed layer; and removing the mandrel in such a way that the plated metal and plasma spray formed layers remain intact to form a tubular waveguide body with an inner high conductivity liner. The waveguide structure described is a plural cavity bandpass waveguide filter which is fabricated on a mandrel comprising separable sections arranged end to end. Plated iris discs are clamped between the confronting ends of the mandrel sections prior to metal plating plasma spray coating of the mandrel, such that when the mandrel is removed, the iris discs remain intact with and peripherally joined to the filter body liner to define the resonant filter cavities.