I have the old Planetary Empires set for using in 40K campaigns, however, the set only contains random landscapes and Imperial ruins. For our dynamic campaigns, I am making simple faction specific tiles for some of the major armies.
Here is the first set of Imperial tiles! Included are an Astartes forward base, an Imperial Guard base, and a missile silo. Both of the bases serve the purpose you think they do, while the missile silos make great offensive bonus tiles allowing for a free bombardment of enemy troops before the start of the first battle round so long as you hold one. If you require peg holes for flags and upgrades in any of the tiles missing them, just drill a 7/64" hole through the tile in the location you feel is best. As always, enjoy!
Also remixed in is an epic scale Astartes Stronghold, which Thingiverse can't seem to find when I add it as a source, so here it is: https://www.thingiverse.com/thing:1862257