Pretty much all you want to do is hollow out a disk drive I used a large one because it fits a raspberry pi better.

Then I opened the disk drive a bit so when I placed the pi inside the disk drive could still function but with out being able to read disks.

After that I place the cables out the back of the disk drive and then put the disk drive back together and then screwed it back in the the tower.

Then I put the usb cable out the back in to the usb port and the same with the hdmi cable.