Lately I finished the work on the power cables, connected everything and temporarely secured everything with scotch tape.
The circuitry is still pretty easy done because all black wires go to the ground pin on the pi's gpio and the red ones to one of the 5V pin's. I think I'm going to add a protective diode a fuse and a capacitor to smooth out any voltage variance.
As you can see, I haven't progressed in finnishing the case. I've discarded the idea of a triangular shape which was sort of problematic and moved to a standart box shape but to finish this, I have to buy more metal and return to the workshop.