Caravan-mining is a thing now. Build long-range scanner and send your guys to mine the stuff. You'll get about ~400-500 per map.
TBH plasteel should be premium mineral that isn't that easy to sustain. Otherwise there is little point in playing in late game, since you're swimming in it.
TBH plasteel should be premium mineral that isn't that easy to sustain. Otherwise there is little point in playing in late game, since you're swimming in it.