After a little research, I found this great idea for doing a light saber cake.
First, I baked a simple, 9x13 chocolate cake and iced it blue (which was a colour that was more-or-less chosen at random). Then, I iced three Vachon chocolate swiss rolls with green icing and placed them on the cake and then I iced three more swiss rolls in red. Finally,I used a little bit of black icing to ice two more swiss rolls, and placed them on the cake as light saber handles.
And for the finishing touches, a couple of LEGO Star Wars guys.
I must admit, I was pretty happy with the way the cake turned out. But more importantly, Austin loved it. And so did his friends at the party -- for a few short minutes before it was cut up and devoured, I was the cool mom who made a cool cake.