Here's some pictures first.

My mock up:

Here it is with the shelf open:

Minus the highlighter holding the shelf up.

Here's where it goes:

Here is the problem, it fits everywhere(well it will when I do some more cutting) except depth wise. This is what's in the way:

I think I can get rid of the metal strip, but behind it I think is the air duct for the floor vents. I'm not positive on that though. Any suggestions? My other thing I was thinking is that I could raise it, instead of dropping it, from the bottom of the cubby. There is a lot of room under there. My only problem with that is that if anything spills it will go right down to where the computer is. Plus dirt and dust are more likely to collect there. I would basically be putting it on the floor or close to it. It would get pretty dirty down there, and I was afraid of it sucking up to much dirt/dust with the cooling fan. By the way it's going to be a Mac Mini.