Combine all of the ingredients except for the essential oils and mica in a quart-size mason jar. Carefully place the jar in a small saucepan of water on the stove. Or use a double boiler if preferred.
Bring the water to a low simmer. Stir the ingredients constantly until melted and smooth.
Remove from the heat and stir in the essential oils and mica.
Carefully pour the mixture into your molds.
Allow the lotion bars to cool completely before popping them out of the molds.
Notes
Instead of individual molds, you can pour the lotion bars into a square silicone baking pan before cutting them into bars.