I was trying to get a foamy material like coffee latte with material shaders. tried the procedural shader in the share forum but render times were unexceptable and controlling the look was difficult.
The result with four layers of stenciled meshes stacked. Looks foamy!
I rotated the photoshopped textures of the drawn holes on each layer so sometimes they overlap and you can look deeper into the foam..
Next thing to work on is to create some displacement to get some transparent bubbles covering the holes and some speculars.