Several bits, slivers, and pieces of used soap - enough to make 1 cup, dried out, or 1 cup soap flakes
1 cup boiling water
If using soap bits, grind them in a food processor blender until they are fine. Mix with the soap flakes, if necessary to make 2 cups. Pour boiling water over the soap and stir until soap is completely dissolved. Cool. Label and store in a pump-type dispenser or a squeeze-top plastic container.