My attempt at an embossed metal box from beverage can

I was inspired by a makezine.com article I was reading this evening, and decided to follow a tutorial to make an embossed box out of an aluminium can. I haven't done anything creative for a long time, and I really enjoyed it.

I'm not sure if sanding the outside of the can is completely necessary, since its only visible on the inside of the box. Also, a ballpoint pen isn't the best tool to use, since it leaves blue ink everywhere.