Namely, the metallic mass 12 may be formed as follows: First, powder or particles of a suitablemetallic material(s) are mixed with a lubricant such as zinc stearate, and pressed into a mold to form the desirably shaped metallic mass 12, and then sintered or heated in an atmosphere of suitable gas, to a temperature below the melting point of thealloy where solid-state bonding of the particles takes