Start with flat-finish latex paint in any shade. For small areas, such as a door panel, mix 1 cup at a time. Pour 1 cup of paint into a container. Add 2 tablespoons of unsanded tile grout. Mix with a paint stirrer, carefully breaking up clumps.
Apply paint with a roller or a sponge paintbrush to a primed or painted surface. Work in small sections, going over the same spot several times to ensure full, even coverage. Let dry.
Smooth area with 150-grit sandpaper, and wipe off dust.
To condition, rub the side of a piece of chalk over entire surface. Wipe away residue with a barely damp sponge.