take the top off the dvd drive.
not to say you didn't find it out yourself but this was posted back a couple days on max console or xbox scene. don't remember which.
i made a junkyard map just using three man cannons and dropping random crap on them shooting it into a pile. It worked pretty well.
It may be pretty sweet if you do it. Just make landmarks and such. Also don't just like throw weapons in stupid spots where people would think you'd have to be...