Hello,

I have downloaded and printed at FabLab a parametric yinyang cylinder (downloaded from http://www.thingiverse.com/thing:22682)

You can also directly download the .stl file here:

Printing two identical parts you can compose an awesome 3D yinyang. Here a couple of pics of the parts printed at FabLab:

The overall quality is quite good. You can observe even a good quality on the external texture:

 Definitively, the smoother designs are better printed with the filament 3D printers.