1 to 2 drops each of green, yellow, red, and blue liquid food coloring
How to Make It
Place 1/2 cup sugar and drop of green food coloring in a jar or zip-top plastic bag; seal. Shake vigorously to evenly mix color with sugar. Repeat procedure with 1/2 cup sugar and yellow food coloring. For purple, combine 1 drop red and 1 drop blue food coloring before adding to remaining 1/2 cup sugar.