The child paints the whole rock in their chosen base colour using a medium brush. Two thin coats give better coverage than one thick one. Wait 20 minutes between coats. The rock should be one solid colour with no original stone showing through before moving on.

Choose two googly eyes of deliberately different sizes for a lopsided, comic-book monster effect. Dab a good amount of craft glue on the flat back of each eye and press firmly onto the rock. Hold for 30 seconds each. Leave flat for 10 minutes until the eyes are fully set and do not slide.

Use the paint pen to add teeth, a mouth, spots, claws, eyebrows or whatever the child wants. The paint pen tip gives a clean line that a brush would not. Let the ink dry for five minutes before handling. The monster is finished when you can pick it up without the eyes rattling loose.