If you're frugal and hate to waste even the smallest sliver of soap, don't despair. One solution is to save all your leftover soap scraps and reprocess them into a new bar, also called hand milling or rebatching. You will not only save money with this simple and inexpensive project, but you will also be recycling. Use your new bars of soap yourself, or give them to family and friends as gifts.
Gather all of your leftover soap pieces. Grate each soap piece with a grater until you have about 250 ml (1 cup). Cutting the soap into tiny pieces works, too.
Fill a saucepan halfway with water and place it on the hob, turning the burner ring to medium heat. Next, place the glass bowl in the pan, making a homemade double boiler.
Pour the milk into the glass bowl and then add the grated soap. Using water instead of milk also works well.
Stir the soap mixture often to ensure that it does not stick to the bottom. Once the mixture has melted, remove the saucepan from the heat.
Spoon the melted soap into the cupcake tins. Alternatively, plastic containers, moulds or even milk cartons can work as moulds for your soap.
Put the soap aside so it will cool and harden to the touch, which usually takes between three and four hours. Placing the moulds in the freezer for one hour will help speed up the cooling time.
Remove the soap from the tins and place them on a wire rack. This will help the soap to harden completely and can take up to a couple of weeks. Once the soap is cured, or completely dry throughout, you can use the soap.