Is there any real-world material that is both reflective and transparent in 3D? A simple plane of glass is 3D and transparent, but reflective only in two 2D planes. I'm looking for something that is reflective in a large number of parallel 2D planes so that the reflection has depth. How about if each surface reflects a different polarization of light? One could have layers with different angles of polarization. But I don't see how the light would get back out after being reflected. The polarized layer would have to be a mirror in one direction and transparent in the other.