Mix sand, cornstarch, and dish soap in a medium glass bowl until well blended.Stir in glue, desired food color(s) and extract(s) until well blended and you get the color and smell you want. (Or, download our color and scent mixing guide above to see some of our cool, colorful and yummy-scented slime ideas.)Stir in contact solution, 1 teaspoon at a time, until mixture becomes difficult to stir and is no longer sticky. (If necessary, add more contact solution until desired consistency.)Knead in hands until you form a ball that is slightly wet, but does not stick to hands. (Slime is ready to use when you can touch the slime and pull your fingers away without anything sticking to them.) Store slime in an airtight container when not using.