Nice solution, clearly described - thanks
Raz, have you considered running channels on the box sides as well?
An alternative, which wouldn't work so well for those dividers but is stronger and quicker for tie-down, is
E-track (just Google search for lots of products and descriptions, including
McMaster-Carr). E-track provides attachment points at a fixed interval (I think it's 2"), and the fittings lock with a spring-loaded catch, so no tools are required; the strut channel approach allows placement anywhere you want, but requires a wrench (
unless you use wing nuts) and is limited by the grip of the nut (maybe not an issue for reasonable applications).
Edit note: Raz doesn't need a wrench because he's using wing nuts. Thanks for the correction!