>>545131750
i think you mean a main bus

the idea is you have some resources that are used in basically everything you want to produce in the factory (say iron and copper plates, steel)
you have just a straight line of belts those resources and then you build a line of X assembly machines perpendicular to that
then for the next set of things you want to make you repeat and just extend the straight line of belts of the "bus" as needed

one thing you can do is go to the gallaxy and just click on random people's bases and look at them
like this section is obviously a main bus