multi-mobo case ideas needed

I am going to build a big case out of mdf to house my server and a some folding rigs. For now it will only have 2 systems but I'd like room for a total of six.

Any ideas how it should be layed out? I'd like it to be as small as box as possible, but still need room to get in and work. I'm thinking taller would be better to have a smaller footprint.

And one last thing, it will be cooled by one big water system, for noise reasons.

I was thinking a vertical cabinet with the mobos mounted horizontally, and slide-out mobo trays for easy access. But that would be difficult with water cooling.

Thanks for any input.