If you do not have any citric acid try cream of tartar instead.
Mix together 2 parts baking soda to 1 part citric acid in a bowl (2 tbsp to 1 tbsp)
pour 3 tbsp of water and a few drops of oil or scent and a few drops of dye/colouring into a spray bottle and shake.
Slowly spray 1 to 2 sprays at a time to the dry mixture until it begins to stick together.
Transfer the mixture into moulds and press together.
Leave in the moulds to dry. When ready tap them out and wrap in tissue paper and tie with ribbon.