Xbox 360 Case Mod Cutout Question?

I'm looking to mod my xbox 360 case and do something cool. However I need to cutout words in the plastic and then do plexi below the case. I run into a problem where say i cut out the letter "o" the outside of the o is where the light will shine through and i will need the inside to stay there intact. However I can't do that since there would be no plastic holding that in place. A perfect example is this Tron Legacy case I found: http://walyou.com/tron-legacy-xbox-360/ . I don't know if he cut out the pieces then attached them to the plexi below? Any help is appreciated!