Combine baking soda and citric acid in a medium sized mixing bowl.
Stir and work out lumps with a spoon, whisk, and/or your fingers.
Combine melted shea or mango butter and essential oil.
Drizzle the melted mixture into the dry ingredients while stirring, breaking up any clumps with your fingers as needed.
Squeeze a handful of the mixture.
If it holds together in a ball, it's ready. If not, spray 1 to 2 spritzes of witch hazel into the mixture and stir, then test again.
The mixture should look on the dry side, but still squeeze together into a ball without crumbling when it’s ready.
Sprinkle a few pinches of ecofriendly glitter inside the bath bomb mold halves.
Fill one half with the mixture, pressing lightly as you pack it in.
Place a mini snowflake soap inside the mold and lightly press it in. Cover with more bath bomb mixture to overfill.
Fill the other half of the bath bomb mold with the mixture, overfilling it past the top.
Press the two halves together, cleaning out any extra bits that squeeze out from the edges with your fingers.
Try not to overly twist the mold when you do this, or it could break the bond between the two halves.
Carefully try pulling the top half of the mold off. You may need to tap the mold with a knife or against the table or counter to help it loosen.
Sprinkle with a tiny pinch of additional glitter, if you feel like the bath bomb needs it. Keep the bath bomb in the bottom half of the mold for about 10 minutes.
Place the top of the mold back on the bath bomb, flip it upside down, and remove the other half of the mold, allowing that side to air dry for an additional 10 to 20 minutes.
After removing the bath bomb from the mold half, place it on a towel, covered with a sheet of wax paper.
In dry climates: Allow to air dry for several hours before packaging
In high humidity climates: Package the bath bombs as soon as they’re firm enough to be handled so they don’t absorb moisture from the air and expand.
Some climates may have the best luck by placing the finished bath bombs in the refrigerator for a short while to solidify and air dry before packaging.
Use the bath bombs up within 2 to 4 weeks.