I have 3 batteries for my powerbook that i switch in and out. They tend to get confused at meeting points for mac users such as conferences so I thought I'd label them via laser etching.
Step 1: Select a File or Image for Marking the Back of the Battery.
Step 2: Place in Laser-etcher's Bed. Eg: the Epilog I Have in My Shop.
i referenced it to the top corner and used the alignment features in Corel to make sure it was in the right spot.