The shell kit came with 2 small brass hinges and 8 brass screws to fix them on the lid and main body. The gaps to insert the hinge leaves in the main shell were nearly as wide as the round knuckles diameter. I thought that should be enough space to get some thin and flexible wires through the hinges to connect the electronics from the main body with the door.
I removed the pin with a hammer and a small flattened nail to separate the hinge parts. On the leave with two knuckles I carefully filed little dents to approximately half of the knuckle connection (this took a long time, filed by hand). On the leave with three knuckles I filed away a small part on the bottom side of the middle knuckle so that there was a small gap left to guide through the wires.
I splitted the long hinge pin and made two short pins that only go through one and a half knuckles. In the middle of the hinge the inner knuckle holes are used to guide through the wires.
After some test fittings I extended the hinge leaves for the main body by gluing on short 1 mm thick ABS stripes with ultra-strong 2-component epoxy. After letting it dry overnight, I drilled holes for M3 screws and shortened those screws. In my tests I was able to get four very thin and flexible, stranded copper wires through each hinge – that looked promising!
The main body had thicker wall supports in the area of the hinges, probably to be thick enough to get the screws in that came with the kit. I removed these supports because I wanted to glue in nuts to be able to easily remove the hinges during the following building process.
The local hardware store only had M3 nuts and screws in stock, so I used them. The screw heads were quite large, but the height of the nuts was perfect for getting the hinges in the ideal position.
I secured the body with inserted hinges in a stable, upright position before applying the first small dots of epoxy glue to hold the hinges in place. After letting it dry completely overnight I carefully unscrewed the screws and removed the hinges. Then I applied a lot more of the ultra-strong epoxy around the nuts and let it dry overnight again.