Reach up to the skies or dig deep below, expand your base vertically... If you're into that kind of thing. Original by Simcra, ported to 0.14-0.16 by Erdbeerbaer. Port to 0.17 started by DeltaNedas and continued by Danacus.
Awesome mod, shame at how tedious mining out the walls are. Do you have any mod recommendations for speeding it up? Or maybe adding compatibility for things like the miner vehicle or the mining drones to be able to mine out the walls like rocks or stone ore?
It's easier to mine walls in my new mods (https://mods.factorio.com/mod/Surfaces_API), however I haven't done enough testing and don't have a lot of time to fix bugs at the moment. So use them at your own risk.