The reality of stackable tool boxes is that they need to be spread around the jobsite for the contents to be accessible.
The author uses plenty of commercially made boxes but transports and stores them in rolling cases that allow him to access them one at a time. The modular design of his cases allows any one case to accept any of the brand-name storage systems he owns. He often discards the blow-molded inserts included in brand-name toolboxes, as these tend to make inefficient use of the space inside the box.
Foam inserts are a nice way to organize tools and keep them secure in a toolbox, but they take up more space than tool rolls.
The author often carries a portable cordless case, similar to his larger rolling case. It is sized to fit on the Milwaukee Packout system.
The portable cordless case doubles as a step stool and task oriented workstand.