For all my permanent adhesion solutions, I prefer two-part 24-hour epoxy. The kind th at you squirt out of two separate tubes, then mix up yourself, then apply. Sure, it takes a full day before it's completely set and hardened and all that, but I've found the 5-minute stuff is too brittle and won't stand up to repeated handling / use.
It takes about 20 minutes to form the initial bond, but 24 hours to reach full strength. On the two bottles it says 'LePage 11 regular epoxy glue'.
I don't recall ever using it on a Mac, but I've used it on a lot of other electronics and all kinds of other projects, and it's good stuff. Of course, as always, your mileage may vary.
She who laughs last -- probably made a back-up.
Depending on the nature of the damage, putty-type epoxy might be a better alternative. It's 2-part, you knead it to mix, and sets fairly quickly. You can final shape it later (sanding, cutting, etc) but depending on the job it might be easier to handle, and it excels at filling gaps. You can paint it, but typically it comes in a rather dark colour anyway.
Sold under a number of brands, and also it's the stuff at Canadian Tire under "Gas Tank Leak Repair", etc.
The long-cure epoxies are stronger than the 5-minute ones, but even with the quick epoxies it's best to wait the full 24 hours before stressing the repair. Epoxy cures generate heat and isn't appropriate for everything (some foams and plastics can't handle the heat of curing). If that's the case, you need to use an alternative adhesive.
Epoxies are not easy on the skin; sooner or later you will get a contact dermatitis if you don't wear gloves, but most people don't handle it enough to get a reaction. Wash immediately after you're done. No smoking or eating until you've cleaned up.
When mixing, be careful to use identical amounts of each part; any variation will weaken the final cure. Toothpicks, disposable plastic spoons and knives, cardboard (eg matchbook covers) come in handy.