In a small bowl, combine castile soap and essential oils.
In a medium size bowl, combine dry ingredients.
Add liquid soap mixture into dry mixture. Stir well until consistency similar to wet sand.
Press mixture into cavities of silicone mold or ice cube tray. Leave a little space because ingredients will expand slightly.
Let sit at least 4 hours to dry. Once dry, store DIY toilet bombs in an airtight container for storage. I do not keep any mixture with essential oils in plastic containers. Should be kept at room temperature in a dry place out of direct sunlight. If stored properly, they last 3 - 4 months.