Quasimodosbelfry
500+ Head-Fier
I know, right!Those cases with slots are exceptional.
The dividers are repositionable. Here are the methods from the site. The page (http://www.vannuys.co.jp/n_cable_box/index.html) has more different configuration options.
They're hard to find outside of Japan and when they're available, they tend to be marked up a lot. Try Amazon.co.jp, quite a few VanNuys products are available there.