I've been trying to chip away at the literal pile of cow skulls in my yard this summer! Thanks to my brother I have a pretty good stockpile of skulls to work on, which is great since it gives me the freedom to try new things.
I have this "idea folder" on my desktop for saving images I stumbled across online: photos of places, textures, patterns, objects, etc. that interest me or spark an idea. This skull was based off a pattern that I saw and saved a few months ago. The color scheme is very different from the photo but the motif is very similar.
I haven't done such a monochromatic skull in the past, but having a quart of leftover slate paint from the storm drain project means I have some material to use up! I started by skipping the primer and just covering the entire skull with gray paint. From there I free-handed the design and just started hand painting and drawing the pattern. The final step was to paint the nostrils/inside with black paint, something that worked well with spray paint.
The only issue I had with this skull was sand: since it spent several years in a Hermosa pasture it was very clean of any decayed tissue but was absolutely FILLED with sand! It was funny: every turn and shift I made while painting it, more sand seemed to escape from little nooks and holes. By the time I was done it seemed relatively sand-free, which is good since I have already found a buyer for this one!