Good contact cement is strong and instantaneous.
There is some so-called latex contact cement that is nice to work with (in terms of fumes and so forth) but, in my experience at least, doesn't actually hold things together most of the time. I don't recommend it at all.
I've generally used epoxy to attach the outer skin to the plywood or whatever. It definitely doesn't let go, but it does require something to hold things in place while it cures. Slow-curing epoxy is much more convenient for this sort of application than five-miute epoxy. (I like the West System epoxies which are excellent quality...but unfortunately not inexpensive. They're available from various places, including Lee Valley for mail order and West Marine stores. Incidentally, West Marine and West System are two separate unrelated companies that just happen to be named for the same compass point.)