My son loves Storm Troopers and had a very specific color and design he wanted, so it made this Storm Trooper Birthday Cake extra special. I started with a 14 inch round cake pan which required 3 boxes of cake mix. After that was cooled and leveled I frosted it with white. I used a picture out of one of his star wars coloring books for the outline.
I put a sheet of wax paper over the picture and traced over the basic lines with a marker and then free handed the specific features my son wanted on the mask. Then I used black piping gel and traced over the lines that I drew on the waxed paper, turned it over and gently placed it on the cake, pressed it down lightly all around and then lifted it off. What was left on the cake was the outline which I then traced over with black frosting (also store bought) and then filled in the colors where applicable with a #21 star tip.
I went over some of the black lines that seemed hidden by the stars when I was done. I used the same 21 tip for the shell border and a #5 for the dots on the side. Pretty simple cake in the end. Good luck!