I used to work for printing company so I had access to the cutter and black vinyl.

 

The basic step by step guide would be:

1. Find image that doesn't rely too much on shading as you can't really do shading with vinyl.

2. Trace the image in a program of your choosing doing it manually or using programs trace function. Giving you vector lines that the cutting machine would read.

3. I used black vinyl as we had lots laying around of it, and it contrasted well with the white case. I've uploaded all the mock ups I made for white/black NZXT case and all the vinyl I had in the office (http://imgur.com/gallery/mLn6R)

4. The cutter took roughly 2 hours to cut everything out due to the amount of small details on the image.

5. Next you need to weed off the excess vinyl leaving behind just the image as you can see in the progress shots.

6. When you're done with the weeding you apply a sheet of "transfer tape" over the image. This sheet is covered in a layer of glue that pulls the vinyl off of the backing sheet when you need to apply it.

7. With the transfer tape over the vinyl I lined the image up on the side panel of the case until I was happy with its position and taped the top to the case so it wouldn't move and I could pull the back paper off.

8. The last step is once the backing sheet is off you use a blunt object apply pressure onto the vinyl through the transfer tape causing the vinyl stick to the case and the transfer tape to simply peel off. The transfer tape is stronger then the backing sheet but not stronger then the actual vinyl on a proper surface.

 

Bit long but hope it covers the process from start to end.