In a medium sized bowl, combine all dry ingredients. Stir well.
Melt the coconut oil and vapor rub together in a small bowl. If you are going to add food coloring, add it into the oil mixture at this point.
Pour the coconut oil mixture into the bowl with the dry ingredients. Use your hands to mix it all together, breaking apart chunks as you go. If you would like to adjust the color, melt a little bit more coconut oil and stir in the dye. Then pour it into your bath bomb mixture and continue mixing.
Pack the mixtures into whatever mold you like. If you are using a ball mold, pack each side until overflowing, and squeeze both halves together to close.
Freeze for 20 minutes.
To remove the bath bomb from the mold, warm the sides of the mold with your hands (this will help melt the coconut oil) and squeeze either side until the bomb pops out.