Made my own small bath bombs while home from work sick, I love love love them and found the mold very easy to use.
I plan on giving them away for Christmas.
Recipe I used was...
1 cup baking soda
1/2 cup citric acid (or tartaric acid)
1/2 cup Epsom salt
1/2 cup cornstarch (Or arrowroot powder)
Mix all dry ingredients in one bowl
2 1/2 TBS almond oil (or coconut)
3/4 TBS of water
12-15 drops essential oil
Slowly add wet ingredients to dry mix- be careful not to make too wet because it will activate the fizzyness before you use the bomb (I used a spray bottle to do this)