In a mixing bowl, combine sugar, meringue powder, and water. Mix mixture for five minutes, or until it is so stiff that knife drawn through it leaves a clean-cut path. If desired, add red, green or yellow food coloring to frosting. With decorating bag, with small tip, decorate cookies with frosting. If mixture is too thick add a little more warm water to desired spreading or piping consistency. Keep frosting covered with plastic wrap to prevent drying out. Decorate cookies as desired.