I've laser etched more laptops than most since I help operate the Instructables laser cutter at Maker Faire and the Web 2.0 Expo, however I've never actually etched any of my own computers.
I decided to put my old PowerBook G4 under the laser for a slightly more experimental and complex etch than I've previously done. Luckily, the technique worked, the etching went off without a hitch, and the computer came out of the ordeal completely unharmed.
Typing on top of your own hands is a little freaky, but I'm definitely enjoying it, and so far, it's prevented any writers block because I'm always ready to type!
Step 1: Photograph hands and computer keyboard
I set a camera up on a tripod and took photos with my hands in place over some white paper so that the image would be easier to trace in Photoshop.
I then took the paper background away and took some photos of just my computer keyboard so that I'd have something to register my hands on.
Step 2: Process the image
Then, I placed the image of my computer keyboard on a new layer and positioned my hands in place over the home row of keys. They were already in the correct general location from the dots on the white paper, but they needed just a little tweaking to be be perfectly aligned.
I desaturated the image (lasers only print grayscale images) and turned up the brightness and the contrast a bit so that my hands really popped.
The last part of the image processing was to resize the image. I measured the distance between two points on my laptop in real life and then resized the image in Photoshop to match that same distance on the screen.
Step 3: Will the laser destroy my laptop keyboard and touchpad?
I knew that the anodized aluminum case would react fine, but since I've never seen anyone etch their keys or touchpad, I needed some reassurance.
Luckily, a co-worker in our space knew an engineer who designed touchpads, and so he gave him a call to get some advice. The engineer predicted that it wouldn't hurt the touchpad, and so having gotten the go-ahead, I took the laptop to the laser etcher.
Step 4: Set up the job
I first etched the image onto blue painters tape laid down on the bed of the laser cutter so that I could see where exactly my hands would be etched.
Step 5: Register the laptop
With several registration points in place, I then slid my laptop into position beneath the skewers and aligned them with the home row of keys where I wanted my fingers to land.
Step 6: Defeat the laser cutter safety mechanism
In order to defeat the safety mechanism, I placed two small magnets on the side of the machine where two magnets embedded in the lid normally rest. This made the laser etch think that the lid was closed when it actually wasn't!
Defeating the safety mechanism was fun. I can see why people break into banks.
Step 7: Test the alignment
Surprisingly, the skewer system I used worked perfectly to register my laptop in the correct location. My fingers fell right into position on the painters tape.
Step 8: Fire in the hole
The power setting was turned down so low because our new laser is more powerful than the old one (75W) and I wanted to take away nothing more than the finish on the keyboard keys. Etching too deep would have created an annoying texture on the keys that my fingers would have noticed every time they typed a letter. That would have been bad. 12% seemed to be just enough power to etch nothing more than the silver finish.
10 minutes later the job was complete and my hands were permanently etched into their home position on my computer. I fired the computer back up, tested the touchpad and typed up this Instructable - all systems nominal.