Make cupcakes according to your cake package directions.
In a large bowl, cream the butter and add vanilla.
Mix in the confectioners sugar one cup at a time.
Beat in the milk
Divide equally based on the number of colors you want to make.
Mix food color into each portion to achieve the desired shade.
Transfer icing to a large sized ziploc bag or icing/piping Bag
Ice the top of each cupcake.
Mix together sugar and citric acid.
Dust the top of each cupcake with sugar mixture.
Place 1 Sour Patch Kid on top of each cupcake.