Hello,

Here is my N900 armored prototype.

I have never seen one like that and you?

That's one of the R&D casings that many prototypes were fixed to when doing early testing on the first devices.

The idea is same as why car manufacturers often paint the prototype cars used on test-drive-tracks to very crazy patterned color; it is to hide the true look of the car or device if someone who is not supposed to see it happens by accidentally.