In a bowl, mix the citric acid and baking soda.
Add the essential oil and mix that in well using your hands.
Pour the witch hazel into the spray bottle and spritz some onto the top of the powder mixture.
Mix the witch hazel in quickly with your hands, spritz some more on top, mix again, and repeat until the mixture packs together easily. Be careful not to get it too moist - if it starts to fizz, you've added too much.
Scoop the mixture into the molds one at a time and pack it down tightly so that it holds together.
Allow them to dry for at least 24 hours before use.