1. Open your bullet in Aniation Shop 3. The bullet should be around 8 px.
2. Zoom into the frames and select the brush tool which looks like this: .
Pick a color and make a border around the edges, like I've done:
3. Now dublicate your bullet three times, by clicking on this: . Pick three different colors,
and fill your bullets with them. Now it should be looking something like this:
.
Pick a color and make a border around the edges, like I've done: 
. Pick three different colors,
and fill your bullets with them. Now it should be looking something like this: 
