In a large bowl, combine the epsom salt, citric acid, cornstarch, and baking soda. Use a whisk to stir the mixture thoroughly for a few minutes, ensuring all the ingredients are well combined.

Add the yellow mica powder to the dry mixture and continue stirring until the color is evenly distributed.

In a separate jar, combine the carrier oil, water, and coconut fragrance oil. Secure the lid and shake vigorously to blend the ingredients.

Slowly add the liquid mixture to the dry ingredients, whisking continuously. Take your time and add the liquid one drip at a time to ensure proper incorporation. Keep whisking until the entire mixture has the same texture throughout.

Fill both halves of the bath bomb molds with the mixture, slightly overfilling each side. Press the two halves together firmly and give them a quick twist to secure them in place.

Allow the bath bombs to set in the molds for about 6 hours. Once they are partially dry, carefully remove them from the molds and let them finish drying completely.

If the bath bombs don't release easily, gently tap the bottom of the molds with a spoon to help loosen them.