Dissolve menthol crystals by mixing them with essential oils or alcohol.

In a separate bowl combine baking soda, cornstarch and citric acid.

Add color if using any.

Add dissolved menthol and essential oils.

Mix for couple of minutes to ensure that all ingredients are well incorporated. The final mixture should resemble damp sand. Squeeze it in your palm. If the mixture stays together, its ready. If it crumbles, spray some alcohol/witch hazel, mix and try again.

Take your molds and pack them tightly with the mixture. Keep the mixture in the mold for a minute and then remove from the mold to dry overnight.

Add couple of drops of essential oils to the finished steamers. Ideally somewhere on the bottom, so it wouldnt be seen.

Store in an airtight container.