Slot upgrades

How to people cope with the slot upgrades? So you want to Specialised a station like the paint station. You currently have a setup from the beginning so no extra slots. Do you now rip all that out at great expensive or build elsewhere? Maybe I have no imagination? I end up having to get money somehow to build elsewhere in the factory.

I am by no means an expert at the game but I build the new lines with the upgrades elsewhere.

I keep the basic line running to generate money and i build the other line with the money the basic one generates. When the new line is complete i start it up, wait for the cars to reach the end of the line and then dismantle the old line freeing up space for more complex lines. This makes the transition from basic lines to complex lines smoother and you dont run the risk of running out of money while you are building the new line.