jokohoko
commented
9 years ago I think you did not get the idea completely right!, the electrode holders or fingers called in the stl's are only to be mounted on the Hand parts (the cube with holders on all 4 sides). So all connectors are mounted with the pins towards the front and the holes towards the back of the bci. this way many combinations are possible.
(Not that i will state this design is finished, but this issue you stated is not an issue!)
The design is not symmetric. You cannot attach any part to any other part. There is no reason for every part to have a "male" and a "female" side, where they could have male and female on both sides (rotational symmetric around the vertical axis). Currently the PCB-holder is male, the arms are male+female, so the ends will always be male. But the electrode holder is male too and thus doesn't fit onto these ends.