Get it? Preparing/cooking a pie? Pi?... *ahem*
It's pretty obvious that the Raspberry Pi won't fit into the Mac's casing, so I'm going to be trimming it down. If you're interested in learning more about this process, you can look up 'diet pi' (or, of course, keep reading). Many online guides suggest desoldering the joints on the USB and GbE (gigabit ethernet) ports, but I found this was impractical, especially when I had a dremel sitting right there. This came with a cost, however: I broke a trace to one of the pads on a USB 3 lane because I wasn't careful enough.
I started by bending back the rear panels to make this as easy as possible. On another (less valuable) Pi I successfully removed half of one USB stack and relocated it. But on this one, I would be removing both. I got to work and soon had only 1 USB port. I removed the shielding on the GbE port only to find... ANOTHER PCB?? Apparently I didn't research this well enough, because in that chonky block there is a set of fragile magnetics... and I ruined them. So I set out to destroy the remains of this interface. Oops.
After that, it was a matter of getting a heatsink and some thermal paste to keep this bad boy cool.