I made this cake for a coworker..I had played around a little bit with buttercream icing but had never really put any piping details into any of the cakes I've made. This was a layered chocolate cake with buttercream filing and icing. Her favorite colors were purple and green. I used food coloring from the grocery store..I was having a bit of trouble getting the right shade of purple. I didn't want to add a lot of food coloring so I just stopped there. I don't have a good Wilton spatula so I had used a butter knife dipped in warm water to smooth out the buttercream.