Here is a typical recipe to make gouache paint. Gouache consists of essentially water, pigment, and gum binder, the same as watercolor paint. The difference is primarily the addition of a white extender, which creates an opaque water-based paint.

Ingredients (parts by weight)
52 baryte (blanc fixe) or calcium carbonate
7 dry powder pigment (any color)
24 dextrin solution (50% by weight in water)
12 gum arabic solution (30% by weight in water)
5 glycerin

Grind the first three ingredients on a flat surface, such as a glass or marble slab, using a glass or stone muller. Thoroughly mix the gum Arabic and glycerin together and then add to the mixture on the slab. Grind all ingredients until a smooth consistency is obtained. Additional water may be added to the paint to vary the consistency.