CorSec Engineering gives you some new options for your terrain with these accessory packs.
From the release:
Our new Flat Pack Terrain accessories are a great addition to any terrain piece. They are made from thin laser cut styrene and come in packs held together by small sprues. We have a variety of doors windows, and vents to add accents to your next terrain project. Packs are available in 15mm and 28mm scales.