Only just stumbled on this and there is less than a day to run, but there is some nice looking buildings and scenery listed including a starport, pipelines and tanks, urban, military bases and more.
https://www.kickstarter.com/projects/177891431/base-system-take-control-of-your-battlefieldLooks like the designs are taken from the Mechcommander 2 computer games, so primarily aimed at the Battletech market, but 6mm scenery is 6mm scenery.
They are so doing different styles related to the different factions of you want something to look a little different.