skulls in paint

[mooneye777]

i shot this truck at a local show and my wife pointed out, to my poor lack of concentration and failing eye sight. that every single flame lick in the paint job has a skull in it. the picture below was cropped from the center section of the rear door. this might be a question for (hot rod paint) to answer. is this a stencil air brush pattern, or what is the process to achieve this. i am sure it was very time consuming to do.