Can I suggest radar stations? Two types-the rotating metal lattice and the ones that look like golf balls?
Also sandbag bunkers and sandbag trenches and walls (spline enabled perhaps?).
Tanktraps? Camoflague netting? Barracks/hangers/equipment sheds?
Love the idea and work so far. If offers good and broad variety from the large to small will prob be a day 1 purchase.
Regards
Slinky