Pour all base ingredients into a large pot. Stir constantly over medium heat until a ball forms by pulling away from the sides. You can now use the additives, knead them into the play dough until blended (1-2 minutes). If using essential oils start with 2-3 drops. Remember that essential oils are concentrated and are meant to be added to a base.
The calming scent and the kneading motion will help your child unwind before bed, or on a stressful day.