Here are some ways of doing fingerprint.

(Can’t find the original author of this image)
The first and more natural method is using directional reaction diffusion.
Take a triangular mesh (size of faces matters), some guide curves and it will give you that (in black guide curves)
For getting 2 colors there are 2 methods

  1. Iso splitting mesh
  2. Vectorize (tool in Rhino 7) using a black and white gradient

The other method is just using offset, Clipper is prefered.

Applying some classical method it could be used for portrait