I am looking for suggestions for a metallic gold coloring to be used to color whip cream frosting for a communion cake. Any recommendations?

I've read in a magazine where you could mix some super gold luster dust with some vegetable oil and brush this on the inside of your piping bag, coating the interior. Then fill with your icing and pipe. It should pipe out gold. You'll have to let me know if that works, I haven't tried it yet....