Weigh your oils and fats and put in a large pot on the stove top on the lowest heat setting. Melt until combined.
Weigh the water in a heat proof container and set aside. Wearing gloves, weigh the lye separately - set that aside as well.
The oils on the stovetop should be around 100 degrees F - if not at that temp, you'll want to allow them to cool until they reach that temp.
Carefully pour the lye into the water and stir until combined. The mixture will get incredibly hot - ensure you don't touch or spill the mixture. Once combined, allow the lye water to come down in temperature, anywhere from 15-30 minutes.
Carefully pour the lye water into the oil mixture; use an immersion blender to blend the mixture until it starts to turn into a creamy, pudding like mixture (4-5 minutes and potentially longer).
Add your essential oils and blend again. Pour the mixture into empty Pringles cans or a soap mold and push to the rear of the counter for 24 hours.
After 24 hours, remove the soap from the mold and slice into bars, 4-5 oz in size.
Allow the soap to cure for 4 weeks