This paper presents a micro-optical pattern-based selective transmission mechanism with a simple modulation principle. The mechanism is composed of a patterned plate and liquid medium, and it does not contain a transparent conductor. The pattern uses 50 μm rectangular pyramid shapes that satisfy a retro-reflection condition. An ultraprecision diamond-cutting machine is used to precisely fabricate the metallic patterned mold, and a hot embossing process creates the micro-optical pattern. The measurement results show that the proposed mechanism displays a much higher optical performance and more durability than the existing switchable glasses in the specific condition. It has specular transmittances of 84.1% in the transparent state and 0.2% in the translucent state, and its total reflectance is 50.4%. An optical simulation verifies the measurement results with a specific analysis.