Place all the old soap bars in a colander and rinse them under the tap’s running water in order to do away with any stray hair or dirt stuck to it.
Once rinsed well, drain the old soap bar well and pat dry with a piece of cloth or towel.
Dispense some rubbing alcohol into a medium squirt bottle and place aside at room temperature.
Using a sharp cheese grater, grind down the old soap bar pieces. Now shift the grinded soap pieces into a microwavable measuring cup.
Place the cup in your microwave oven and turn it on at high temperature. Microwave it for 25 to 30 second until melted completely.
Turnoff the oven for few second, stir properly to make sure there are no more soap pieces and all are melted well.
Turn on the oven again and heat for 20 more seconds.
Remove the measuring cup from the oven and pour the melted soap liquid into the soap moulds.
Squeeze out some rubbing alcohol onto the back of the soaps in the moulds in order to do away with all the possible air bubbles.
Set the soap mould in a cold, dry and safe place until cooled completely and solid.
Once hard, carefully pop the new soap from the moulds and use.