With the help of a laser cutter you can personalize your possessions in really amazing ways. In this example I added a Trilobite image to a friend's phone.
Step 1: Find Yourself a Laser Cutter
Laser cutters are becoming more and more common. This is due to the amazing things that you can do with them and the fact that their cost keeps dropping. I would expect that in another 5-10 years they will be found in every Kinkos.
For right now, there are a number of services that you can go to who have laser cutters. In the Bay Area we have Tap Plastic or East Bay Laser & Water Jet. Once you've tasted this tool you will never be happy without one.
In our case we have a 45W Epilog Mini 24. Shown here: