1/2 cup grated soap (I used Dr. Bronners Citrus Castile soap)*
4 cups water
1/2 Tbs vegetable glycerin (optional: used as a hand moisturizer)
10-20 drops of tea tree oil (anti-bacterial) if you like the smell you can add more if not add the lesser.
Steps
Step 1
Grate bar of soap. In a saucepan add water and 1/2 cup grated soap. Over low/medium heat gently heat without bringing to a boil until all the soap has dissolved. Add in vegetable glycerin and stir well. Place in a jar. After cooling for a short time (30 minutes to an hour) add in tea tree oil and allow to set up for 24 hours, stirring occasionally.
Side note: I used the citrus kind for the smell and because citrus helps cut grease! I usually hate the way liquid castile feels on my hands after I wash them, but not when I made it like this! Also, other types of non super lathery soap should work too (like ivory), although I have not tried that. Important note: do not add vinegar or lemon juice to this because castile soap and acid cancel each other out and you will get a bad product. You can use vinegar as a rinse aid though!