Opening up the drive proved to be a real challenge. There were no screws nor hinges to be seen so, of course, I tried brute force. A few minutes later, I was left with a nice crack in the case. Luckily enough, there was a manual floating around on the internet with instructions to open these things. If anyone is interested, you can find it here: http://tim.id.au/laptops/apple/misc/hdi20_1.4_drive.pdf. Removing the innards from the case wasn't very difficult and after cutting an extra hole in the back for all of the cables, my Pi rested comfortably in its new case.
As you can see, it sits really nice next to the tv.

The floppy slot provides a way to release some of the heat.

And a close-up. I'm still thinking of cutting out the Apple logo and reroute some of the status leds, but I'll leave it like this for the time being.

All in all, I'm quite happy with the way this turned out. It didn't cost me a thing and it has a nice retro vibe to it.
