Hi Alex,
I love your stuff! :)
If you have a look at this picture, ...
... you'll notice that the light panel of the CDU is much thicker than standard panels. Judging from the DZUS height, I'd say it's about 12,7mm (1/2"). So the buttons are probably integrated into the light panel and don't protude through the back plate. (Ups, I just notived that this is a replica - I hope it's a good one ;) )
Cheers,
Stefan
PS: Have been lurking quite a while and this is my first post. :)