I also used one of those wheel-equipped folding milk crate dollies. As an EE, I didn't need any extra containers though. I brought about, 10-12 books or so, and didn't use all of them. Seems like there were other disciplines that came prepared for war though. 3 large plastic storage containers full of books on a dolly... that kind of thing. Lots of rolling suitcases.
I also brought a towel (to sit on if necessary), thermos full of coffee (had to take my coffee breaks), a few power bars, and some gum. Do not bring pencils or erasers in to the room, they will collect them and give them back to you after the exam is over (oops).