A few notes on the recipe: castor oil and coconut oil makes water thin soap. reducing to 10% will help with making it harder. KOH is more water soluble so going 60/40 or even 50/50 will make it harder too. The easiest way to get soap out of a PVC mold is to actually freeze it overnight. IT contracts and hardens up so it sticks less to the container. You can then just wack it on a cement front step and it pops out. Though I like to fill my shaving bowl with it.