Thanks y(oYo)! I did it already. Hope, it will pass the examination.

And... As I wrote it before: here are my works. If you click on the picture, you can download the full, lossless version.
Super Mario Bros 1. [NES-SM-FRG] Custom German Box - based on the original.
(If you have any pictures of the top of the original, please le me know and I will re-touch that part of the box)
Super Mario Bros 3. [NES-UM-FRG] Custom German Box - based on the original.
(To tell the truth, I have the original box and It was based enterily on it. But until I don't make a proper scan, it's just custom.)
Metroid [NES-MT-NOE] Custom German Box - based on the original.
(I made a full research on this. The front and the back parts are based on scans which I found in the NintendoAge database, all the other parts based on photos. If you have time, give it a go and compare it with the french/dutch version: the front picture is a bit altered and has more details and "pixels". It was a real pain to re-construct the german picture, but after all I think it looks quite good.)
Super Turrican [NES-TU-FRG] Custom German Box - based on the original.
(It was my first attempt to make a repro box. It's based on the french/dutch version but with proper german text and fonts. It's not so great, but I think it's quite good if you want to make a german box.)Thanks, if you looked my works and I hope I made some spirit to make another people to create unique repro boxes.