MrClass wroteNice concept. Though gets pretty scary when you have SLI or Crossfire or a lot of hard drives. What is the base board made of? (Plexy Glass, Aluminum...). Also from where did you get that PCI-Express x16 bus extension?
You see, the advantage of this design is that you don't need to stack GPUs to run SLI / CF. Those PCI-E x16 bus extensions are found in multiple sites online. They cannot be easily handmade because you need certain resistance values relative to the length you need (that's what I understood), but they can be cheaply bought. They're an awesome idea.