If you find that your slime is still sticky after kneading it for a while, keep adding cornstarch to the slime and knead it in until you get a good consistency. Slowly add 5 more tablespoons of water, stirring well after each one. Add 3 drops of food coloring (optional).Put 1/2 cup shampoo and 1/4 cup of cornstarch in a bowl.To make the slime, you'll need shampoo of any type - though the thicker, the better - and cornstarch.