Select a rock that is similar to the shape of a turtle. Wash the rock and dry it thoroughly.
Coat the entire rock with a base coat of black paint using the medium paintbrush. Allow it to dry completely.
Use white chalk to trace the image of a turtle onto the rock. Include shell details, facial features and small ovals to represent the front feet.
Fill in the chalk outline with colors such as brown, black, yellow and copper to create the image of a turtle. Mix colors to create unique shades for a more natural look. Rinse and dry your paintbrush often.
For eyes, paint inside small circles with yellow, then dot with black to create pupils. Add a tiny dot of white with a detail brush to create the look of glare.
Allow the rock to dry completely after painting is complete. Spray with a matte, clear craft sealant if outdoor paints are not used.