LUXeXceL is a Netherlands-based company that is experimenting with printing shallow optics using UV cureable polymers on clear substrates.  According to their site:

“On a transparent substrate such as PolyCarbonate, drops of clear UV-cureable polymer are jetted via the inkjet principal. The drop-sizes vary according to graphic design. The UV is cured via strong UV-lamps causing extreme polymerization resulting that the polymer will set straight away. This process is repeated for every layer or pixel resulting in transparent geometrical shapes, optical- and magnifying structures.”

So this is using 2D inkjet printers to build thin, flat optics.  Good for Fresnel lens and other flat optic effects, but not yet for collimator optics.  But the world is one-step closer to rapid prototyping complete optic solutions!