Grate 8 ounces of soap. (Two regular size bars.) A cheese grater works well, as does a salad shooter. A food processor also works.
Sprinkle 1-2 ounces water or other liquid over the grated soap.
Heat on low setting in a double boiler or crock pot. You can also place in oven-safe pot and heat in the oven at lowest setting. Stir frequently to avoid burning. This can take anywhere from 15 minutes to an hour.
When soap is liquefied, remove from heat. It will be somewhat lumpy and translucent.
Add desired ingredients.(For the main photos here, I used Pink Himalayan salt and dried rose petals from my daughter's wedding. I added Rose Geranium essential oil which created a lovely rose scent.)
Stir to desired consistency. Pour (or spoon) soap mixture into molds. I placed some dried rose petals on the bottom of this flower mold.
Cool the soap and remove from mold (place mold into freezer for up to 1 hour to make this easier). Cut into desired sizes and shapes using a soap cutter or a food scraper/shovel.The mold used in the above photo is this one.
Allow soap to dry for several days or more. Note that the more liquid you use the longer it will take to cure.
Dry the soap thoroughly between uses to extend its life.