Abstract: A fluid pressure regulator includes a diaphragm operated leakport controlling low liquid or fluid flow rates. A precisely formed leakage unit spaced from the leakport establishes continuous flow from the input to the output. The leakage unit includes a separate orifice unit having an integral molded body and internal precision orifice establishing the continuous flow. A multiple mold core unit for molding an integral body and orifice including a pair of aligned mold cores have opposed planar surfaces located at the orifice plane. A small gap is held between the opposed end surfaces. The orifice unit is molded as a single plastic element without flash at the orifice. The orifice has a diameter in the range of about 0.001 to 0.030 inches, and may be used in various applications requiring precise low flows. The orifice unit may include an elongated tubular body with an internal orifice molded as single integral members.