Here is my recipe and tutorial https://familyfocusblog.com/make-homemade-bath-bombs-lavender-recipe/
Here is a DIY tutorial for you on how to make bath bombs: https://www.popsci.com/how-to-make-your-own-bath-bombs/
these look lush!
This post should help you out.
2 cups baking soda, 1 cup citric acid and 1/2 cup cornstarch. Whisk well to mix. Add fragrance oil of choice (1/2 teaspoon should be enough) and colorant (if you want). Then I simply used a spray bottle with water and spritzed while mixing until it became wet sand consistency. Put it in your mold and let it dry. When I was a vendor at a farmer's type market, I sold many (as in hundreds of bags).