Place a clean silicone mold on a cookie sheet. This will make it easy to transport to the fridge.
In a heat-proof glass container, sprinkle gelatin powder over boiling water. Stir gently until gelatin is dissolved.
In the same container, add liquid castile soap, salt, and essential oils. Stir gently.
Pour into silicone mold. Spray with rubbing alcohol to get rid of any bubbles (optional).
Place in refrigerator for 2-3 hours or until set. Remove shower jellies from mold and use in shower.