It's not hard to make liquid soap from leftover bar soap scraps. First, grate the soap or chop it finely, then add an equal amount of water and let it set until it gets goopy. If you have a blender, you can use that to help smooth the mixture, or you can whisk or beat it by hand. Put it in a pump bottle left from other liquid soap, shampoo or something similar. Sometimes the labels on those bottles will peel off and you'll have a neat free pump bottle for your free liquid soap.