Grate a bar of soap with a regular kitchen grater. One bar of soap should create about 2 cups of soap flakes. Although you could use these flakes for washing clothes, they tend to leave soap scum on the laundry, especially in hard water.
Pour the soap flakes into a large pot, and add 2 cups of water. Heat the mixture over a medium flame, stirring constantly with a plastic or metal spoon until the soap dissolves.
Pour 1 cup of washing soda and 1/2 cup of borax into a gallon container. Pour in the melted soap slowly. Stir the mixture until the powders dissolve.
Mix in 2 1/4 quarts of warm water, and cover the container. The mixture will gel as it sits.
Add 1/8 cup of the gel to wash a normal laundry load.