Well companies like Fat Dragon Games and Profantasy offer printable to cardstock art that you cut up with an exacto knife, then glue at pre-defined placed to build paper models of walls, buildings and many other 3D objects for use in a true 3D battlemap. Plus there are railroad modelers items, though those are probably in the wrong time era than fantasy setting. Additionally there are many companies who create ceramic buildings, walls, objects that you need to paint. There is even companies that sell the ceramic powder and forms for you to make your own ceramic pieces as needed. I don't know how cost effective such are, but they do exist, and some of them look spectacular - from websites and seeing them at Gencon. There are many sources. I would just Google-fu 3D paper models and the like to see what's out there.