I also thought about this and how tedious it would be which is why I settled for something far more basic and very quick to implement. The station that it is on is designed primarily to host a shipyard though (forward thinking may bite me I know) So there is scope to add such an assembly line in the main factory though it will likely be more for decoration than anything else as I assume that the 'shipyard' will actually just be a single block.
Hopefully magnetic docking will enhance this process, though I also forsee the possibility of it massively over complicating things when you have too many rails too close to each other...
well, with the magnetic docking you can move an entity in many more ways than normally.
normally it can travel in like 2 ways (x,y,z) with magnetic i think you can do more ways, up down forth back left right.
example: docked entity has 1 rail docker under it, it is docked on a rail going forth(Z)
then, rails go up and the entity goes up(Y) then it once at the end of going up there is a line running back(Z).
atm, it would stop right at that line, with magnetic you could put a docker ontop of the core and it can go over that one.
i hope you get this mess..... its hard to explain and i cant get screenshots into the forum easy. side view
[DOUBLEPOST=1433346772,1433346737][/DOUBLEPOST]art by HolyCookie