In a glass mixing bowl combine all of the dry ingredients together with your hand. I wore a glove for this. You can either crush any lumps with your hands or sift the baking soda before adding it to the mixing bowl.
Add the drops of essential oil and castor oil and mix well with your hand until the mixture resembles wet sand.
If the mixture is too dry, then use a fine mist spray bottle filled with vodka or witch hazel to moisten the mixture. Only do 2 sprays at a time to avoid getting it too wet.
Once you can squeeze the shower steamer mixture into a clump that holds its shape it’s done.
Immediately press the mixture into your molds, pressing firmly.
Let air dry for 24 hours before unmolding and using.
Notes
Store these in an airtight container, like a glass Mason jar, away from heat and moisture. This recipe makes 7 shower steamers if using a mini muffin pan. If you use a silicone mold the exact yield will depend on the size of your molds.