1. In a small heat-safe container, melt 1 ounce of cocoa butter and 0.5 ounces of sweet almond oil in the microwave using 30-60 second bursts. Stir in 0.5 ounces of candy cane fragrance oil and 0.5 ounces of polysorbate 80. Mix well and set aside.
2. In a large bowl, mix together 16 ounces of baking soda and 8 ounces of citric acid. To get rid of clumps, you can push the powders through a sifter or break them up with your fingers. Citric acid has a tendency to take off nail polish, so wear gloves to protect your manicure.
3. Add the oil to the powder. Use your hands to mix together.
4. Test the consistency of the bath bomb mixture. It should feel similar to wet sand and hold its shape when squeezed. If it’s too dry, use one hand to spritz the mixture with witch hazel and one to mix.
5. Fill the disk mold and packages with the bath bomb mixture. Firmly compact it in to create a solid shape. Only fill each mold to the inner lip, or the lid won't close. Allow the bath bombs to dry and harden for at least 4 hours or up to overnight, and then remove them from the molds.
6. Mix 1 teaspoon of red mica or kelly green mica with 1 tablespoon of 99% isopropyl alcohol. Use a paint brush to create lines around the outside and down the sides of each bath bomb. If you find the paint is bleeding, add more mica to thicken. If it’s too thick, add a bit more 99% isopropyl alcohol.
7. Continue this process with each bath bomb. Allow the paint to dry for 1-2 hours. The paint transfers when touched, so handle carefully. To use, place the bath bombs into a hot bath and enjoy!