Why not treat yourself to a soap pouch saver, it is not just a soap holder it also doubles as an exfoliating surface to smooth your skin. The best feature is that it is made with natural bristles so it can be composted when it wears out. 
 
How does it work you ask? Place the bar of soap in the pouch and pull the drawstring to close. Wet the soap and pouch and lather. when done hang up the pouch, soap and all, to allow too dry between uses.