In a plastic microwave safe bowl place the marshmallows and water. Microwave for 20 seconds. Take out when completely melted. Add the powdered sugar 1 cup at a time and stir in with a spoon. Make into a dough consistency. You may want to add some more powdered sugar on your hands so it won't be so sticky. Kneed in with your hands and add leftover powdered sugar until powder is all kneeded in.