You will need:
Bar of soap
2 T. glycerin (I found ours in walmart next to the band aids)
1 gallon water or more (explained below)
Essential Oil (optional)
First you will need to grate the entire bar of soap with a cheese grater.
In a large pan mix together half of your water, 2 T. glycerin, and your grated bar of soap.
Heat up your mixture and stir constantly until all of the soap is dissolved.
Once the soap is dissolved, remove from heat and let sit for 6 to 8 hours (or overnight if you wish).
After letting the mixture sit you will notice it turn into a big glob of goo.
Add some more water to your mixture. Continue to stir and add water until your reach the right consistency. If your soap is too thick you may need to heat it up a bit before adding more water.
Most of the recipes I found for liquid soap have you adding the entire gallon of water to the pot right off the bat. After reading comments and realizing that there were so many varied results (some was too watery while other was too thick) I decided that this must be due to the brand of soap used. I ended up using the entire gallon for mine and it was the perfect consistency however I recommend that you start half a gallon and then add more to it later.