Grip box design help

I own a woodworking company and a friend of mine who does videos was complaining about all the stuff he needs to carry and sort for a location shoot. He mentioned some available boxes and storage systems but expressed that he was unhappy with anything currently available. 

I am looking for some feedback as to what would make a good grip gear storage system. We were thinking something like an Applebox but stackable and modular. 

What would you look for in a storage system? Dimensions? Internal dividers? strength? mobility? 

Any and all suggestions would be welcome. 

-Ivan