So this is what passes for a graduate thesis these days? A computer case made out of cardboard?
As many of you have already said, the durability and safety of such a case is dubious at best. Not to mention the fact that, the case is probably the least environmentally troublesome part of the computer. Since I started building my own computers back in the mid 90s, I've only ever used ATX mid-tower cases. The computers have been rebuild many times over, but I continue to reuse the same cases. The nice thing about steel is that it's easy enough to use a dremel to machine a hole for a side-mounted fan or front-mounted USB connectors.
Steel is a piece of cake to recycle, whether your throw it in a bin to be reused or it ends up in the landfill. When steel oxides, it turns to rust, which turns to dust and returns to the Earth whence it came.
Now PCBs... that's another matter. Old motherboards (and video cards, soundcards, modems, etc.), once they've given up the ghost, or outlived their usefulness, are basically inert. The plastic, which would normally photo-decay over a course of hundreds of years, could remain in tact for millennia given that the thin layer of gold is almost completely non-reactive and will never decay or degrade. Fortunately, these days, motherboards contain main of the modules which used to be disparate components (such as sound and ethernet).
Bottom line: cardboard box as a "case mod" project... kinda cool. As a graduate thesis... not so much.