I found this ugly, old, Styrofoam skull at the thrift store for $2 and knew it had potential for our Day of the Dead 50th birthday celebration, but also for a fun addition to my Halloween decor.
First, I painted it white. Then I filled in the eye and nose cavities with black paint. The teeth still had dark paint in the crevices, so I left them alone.
Last, I had a really fun time adding designs with sharpie markers. These started out with some of the traditional designs you would find on Mexican Day of the Dead skulls, but after a while I just filled space with random patterns and dots. Easy, fun, cheap!