Drawer systems like this: http://www.containerstore.com/browse...1&PRODID=67291

Just won't work. They'll slip out over the edges, or get caught when you're opening the drawers. These can make great enclosures for ground dwelling geckos/lizards and such... but not for a BP.

As for getting a square tub... as long as there's plenty of floor space, it doesn't matter if it's square, rectangular, whatever.