This is an optical bench (to test lenses mirrors etc.) with adjustable height on each component. I needed to test a few lenses, and buying an optical bench is very expensive, so I made this one. I had couple of spare 8mm rods and LM8UU bearings from a 3D printer project so I used them. You could probably use any plastic bearing as well. The project did it's job for me however, it is not fully developed. Let me know if you are interested, I probably work more on it.
I have initially shared this in Thingiverse
I am sharing the design also here. ;)