Coat each rock in 3-4 thin layers of green acrylic paint. Alternatively, you could also use a green paint pen, but I find you get a smoother and more vibrant base (and save your paint pen's ink) when using acrylic paint. Let the paint dry completely before moving on.

Using the white paint pen, draw on the eyes. It's best to do white first, so you don't get any other paint on the brush pen's tip.

Use the green paint pen to draw any undereye wrinkles or forehead wrinkles you'd like your zombie rock to have.

Use the black paint pen to create the nostril holes, the mouth and any stitches you want to make. Let dry completely.

Carefully fill in the teeth with the white paint pen.

Use the black paint pen to draw the pupils and outline the eyes.

Optional: Use the pink paint pen to draw brains or an upper lip for lady zombies.

Optional: Use a spray sealant to preserve your Halloween rocks.