The floorplan

While this floorplan probably won't work for everyone because of its size (6x4x6 units or 144x96x144), it may give you some ideas how I planned the hotswap.

Note that my level 0 doesn't have much usable space for things other than hallways, so if your plot can take more on level 0, by all means put it there. Personally, I'd love to have more T1 silos there. Also, the T2 crystalshaper on level 0 may be replaced by a T2 pawnbroker once the crystalshaper on level 1 is complete, and that the planned shrine or pawnbroker on level 4 may be replaced or added to with the confectioner room we've told is coming in January.

All of the machine rooms of the indicated type can be placed in the area reserved for it, regardless of tier. Note that most of the doors out of the machine rooms will be plugged up and not lead anywhere, no matter what tier the room is, and there is a large amount of reserved space on other floors waiting for when I can replace lower tier machines with T5 or T6 machines. That's the price of being able to hotswap them. Still, everything is pretty centrally located, with ease of passage from one level to the next through spirals or halls.

The T3/T4 Hall isn't really changable once any other rooms are built off it, as because those other rooms would have to be deleted. So everything above it will be built and upgraded as much as possible first, to see if we can just put in a T4 Hall and get the extra silo or library on Level 5.

You're limited to one library of each tier, so what I put on higher levels may affect what gets filled in on level 6.