Since I found out about @wermy project, I've been wondering if we could make something along the lines of Florian Renner's concept reality. It's an awesome design, one that combines retro appeal with a modern approach masterfully.
I still haven't finished my GBZ project (on a trip actually) but I'm just putting this out there in case it sparks anyones interest.
I'd guess that with a 3D printed case and most of GBZ's project parts, with the exception of a different screen maybe, it should be pretty simple, along the lines of the Wii U gamepad project.

To see more images: http://florian-renner.com/game-boy-1up