I have measured the battery and drawn a model of it. It can be downloaded from this project page in case anyone wants to use it for their own project. Consider the model to be under CC-BY-SA 3.0 license (may be changed if Nikon gets upset), however if you would feel any urge for even more copyleft license, I can release it under WTFPL.

Right now, it is only the outer outline of the battery. No pockets inside, no features for fixing the PCB inside. Will come later, stay tuned!