Optical grade LSR, a lightweight, flexible and tough material, is a silicone-based substance which Proto Labs Inc. says is second only to glass in clarity. The company says LSR can be used to create a wide range of objects for automotive and outdoor applications as it withstands yellowing when subjected to UV light and heat, and that it can be used in molds due to it's low viscosity. It's also crack and scratch resistant. You can read more about LSR material here: http://3dprint.com/46854/proto-labs-lsr/
Below is a picture of some optics 3D printed using this new LSR Optical material. What do you guys think?