In a small small glass, mix 8 to 10 drops of soap dye into 2 teaspoons of water. Slowly add to the bowl, a half teaspoon at a time, continuing to whisk the ingredients the entire time to avoid activating the citric acid.
NOTE: A little bit of fizzing is okay and probably will happen. Just keep stirring until ingredients are well combined and will slightly stick together when pressed. If ingredients continue to fizz and/or swell, you have probably added too much water and activated the ingredients.