You will need rubber moulds for this project, ice cube ones work well.
Crush down the baking soda with a mortar and pestle and then place it in a separate bowl.
Pour the witch hazel, lemon juice, food colouring and aromatherapy oils in to a spray bottle.
Spray the soda until the mixture starts to stick together.
Compact in to the moulds.
Press the bombs out on to a plate and leave to dry for a few hours.