Fat Dragon Games have a new cardstock terrain kit available:
From their announcement:
Winterhawk Ruins provides you with everything you need to make multi-level modular ruined buildings and structures. Utilizing our exclusive E-Z LOCK terrain system, your builds can be dissasembled for easy storage and rerranged for new construction designs as desired. The floor tiles are available with 1? and 1.5 inch grids, and layer options allow you to fully customize your models before printing.