Put the oil, citric acid, baking soda, cornstarch, and essential oil(s) in a glass or porcelain bowl. For relaxation, try relaxing oils like Lavender. For a mood pick-me-up, try a citrus essential oil. The possibilities are endless!
Mix well with your hands until a soft dough is formed. It should feel like damp sand. You could add tried herbs, flowers, or food coloring as well.
Put the mixture in a bath bomb or silicone mold or wrap into a ball shape in Saran wrap and let it sit for 24 hours before removing from mold.
The DIY bath fizzy bombs are ready to use once they've completely dried. Simply drop them in the tub to dissolve.