Gather latex paint
Gather calcium carbonate or plaster of Paris
Gather water
Mix 1 cup latex paint with 2 to 4 tablespoons calcium carbonate or plaster of Paris
Add a small amount of water if needed to thin the mixture
Stir until smooth and lump-free
Test the consistency
Add more powder to thicken or more water to thin
Use immediately or store in a sealed container
Stir again before use