I laser engraved a Canon G11 onto an brushed metal phone battery cover for my Samsung Galaxy S3.
The battery cover was purchased from ebay and it took about 3 or 4 weeks to arrive. I selected one without logo on it. Make sure you have proper ventilation installed, I have no idea how toxic the fume is.
Measure the battery cover. Take a plan view photo of the battery cover or look for one online. Import the photo to your favorite vector graphic editor. Resize the photo the match your measurements.
Decide what graphic to use. There are tons of free/paid vector graphic available online, or you can always make your own.
I decided to use my Canon G11 camera. First I imported a photo of the G11 camera onto solidworks and traced the line. The camera's profile did not match the phone's so I just stretch some lines here and there to match battery cover profile.Then I exported the sketch drawing to CorelDRAW to add the text. Finding fonts to match the camera font took a bit of googling.
To make sure the battery cover is at the right position, first do a cut out. I used 1/8" mdf. Secure the wood with tape.
Then place the battery cover in to do the rest of the laser cuting/engrave. Adjust the height again.
Settings on my 40W laser cutter:
Vector Cut (lines):
FYI, the brushed metal phone battery cover does reduce the phone's reception.
For better image see my flickr