I've been thinking of a paint project that goes something like this:
1. Spray paint a large area of the board
2. Let the paint dry.
3. Coat the paint with a protective coating that can be removed with a light solvent without removing the paint.
4. Cut out an area through the paint/coating to the bare wood.
Repeat steps 1-4 as necessary.
When done, remove all the layers of protected coating down to the finish layer of paint.
It would take some planning to get it looking good, but it seems like a good project for a cnc router.
I don't know what kind of coating would work. Maybe something like a vaseline on a water base paint?