I don't like those big socket organizers. There's nothing wrong with the way they're built; I just don't like that they're dictating how they're organized for you. That's what I like about the Ernst rails--if I want to put a 1/4" drive u-joint next to my 1/4" drive 8mm, I can do that. I lay them out in the way that makes sense for me. I don't have a tool box yet but when I get one, I will probably put all of the commonly used sockets for a Defender on one rail so that I don't have to fish through 16mm when I'm looking for the 17mm. If you have only the ones you need in a row, you can quickly pick them out by sight and wouldn't even have to look at the marking.
The Ernst would solve this but you could do the same thing with a 3D printer. You could build one of those trays with your own organization, which would be really cool. In terms of CAD layouts, it would be really simple, too--a great first project.