Awesome question!
Before modern chemistry folks would make their own paint using pigments from earth, plants and minerals (and other things- I will create a second post about). Often they used a binder such as lindseed oil, egg, milk or honey.
Here are some modern recipies courtesy of Homemade Art:
The following are some simple recipes for a multitude of project paints.
Puff Paint
Ingredients:
⅓ cup White glue
⅔ cup Shaving Cream
Food coloring
Small Container (glass baby food jars work perfectly)
Paint brushes or craft sticks
Steps:
Begin by pouring the ⅓ cup of white glue into a small container. Stir in a few drops of food coloring. Add the ⅔ cup shaving cream to the glue and food coloring mixture, stirring until all of the shaving cream is colored. Adjust the color by adding more food coloring if necessary. Paint the puff paint onto your projects very thick so it will provide the right amount of puff effect. Make several batches and color each with a different color. Store the puff paint in tight fitting jars.
Finger Paint
1 envelope unflavored gelatin
1 cup cold water, divided
½ cup liquid laundry starch
2 cups hot tap water
½ cup mild soap flakes or granules
Food coloring
Soften 1 envelope of unflavored gelatin in ¼ cup of the cold water. Set aside.
In a medium saucepan, combine ½ cup liquid laundry starch with the remaining ¾ cup of the cold water. Using a wooden spoon, stir in 2 cups hot tap water and cook the mixture over medium heat. Bring it to a full rolling boil and continue to cook until the mixture has completely thickened. Remove the saucepan from the heat and stir in the softened gelatin. Add the soap flakes and continue to stir until the soap has completely dissolved. Add up to 1 tablespoon of food coloring to each batch of paint.
Translucent paint
4 ounces white glue
¼ cup liquid laundry starch
Food coloring
Mix 4 ounces white glue with ¼ cup liquid laundry starch. Add several drops of food coloring until you reach the color desired. This translucent paint works well for easel painting. Store in tight fitting jars for up to one week.
Crystal Paint
Ingredients:
¼ cup hot tap water
3 teaspoons Epsom salts
Mix ¼ cup hot tap water with 3 teaspoons of epsom salts. This crystal paint works best when painted on dark colored paper. When the paint is dry, the salt will form crystals that will shimmer and shine in the light.
Face Paint
3 tablespoons solid shortening
2 tablespoons cornstarch
Food coloring
Mix together 3 tablespoons solid shortening and 2 tablespoons cornstarch. Add several drops of food coloring to achieve desired color. Apply the face paint with your fingers or with a small, stiff bristled paintbrush. This face paint can be cleaned off with the use of soap and water.
Sidewalk Paint
Ingredients:
¼ cup cornstarch
¼ cup water
Food coloring
Mix together ¼ cup cornstarch with ¼ cup water. Add several drops of food coloring. This sidewalk paint is a thin paint that may require several coats on the sidewalk to really show up well. Since cornstarch is biodegradeable it makes a perfect sidewalk paint that can be safely washed away with water.
Watercolor Paint
Ingredients:
1 Kool-Aid packet – any flavor or color
2 teaspoons water
Mix 1 packet Kool-Aid with 2 teaspoons water. The Kool-aid will add a nice fragrance to the watercolor paint.
Cornstarch Paint
3 teaspoons cornstarch
2 teaspoons white vinegar
Food coloring
Mix 3 teaspoons corn starch and 2 teaspoons white vinegar in a small jar. Add several drops of food color until you have reached the right color consistency. Cornstarch paint is a very smooth paint that will adhere on most paintable surfaces.