So our build is now done. I'm still thinking about making some improvements, like a proper ports panel or some air circulation control, but it's already very usable NAS box. The only missing part is installing something like freeNAS or some other user friendly NAS OS, but there's a ton of howtos out there, so I'm not going to create another one.
Feel like building your own NAScrate? Here are all the files you'll need.