By developing a pyramid-shaped reflector, we were able to remove the optical filter that causes the decline in light efficiency in existing systems. A pyramid-type glass optical multiplexer (MUX) can be designed for beam coupling efficiency <60% in a combined module. The module was designed and optimized using CODE V, which utilizes nonlinear curve fitting numerical analysis. Based on optical design data, aspheric grinding paths were developed using ULG APS software. Tungsten carbide optical MUX mold cores were fabricated with an ultraprecision grinding machining device [ULG-100C(H3)] and optimum grinding machining of optical surface roughness (<60 nm, angle tolerance <±0.05 deg). Pyramid-type optical MUX was fabricated using the hot press molding technique, and it was measured by using a contact geometry measuring device for reflection angle and angle uniformity. The measurement data were suitable for 49±0.05 deg, which was the design criterion. In addition, angle uniformity was <99.985%. A pyramid-type glass optical MUX molding technique was developed using an optical mold design, ultraprecision grinding machining technology, and a hot press molding system.