Marcos at Topsolitario offers a set of free paper models of cargo containers for your modern and futuristic miniatures games. They are quite lovely. There’s even a video showing how to build them.
The Paper Toy Construction Set is a collection of jpg images of struts and girders in a variety of sizes, shapes and angles. The idea is that you print out these pieces and then use them to build your own models — much like an erector set.
I’m not at all sure what scale this free paper model of an elf tower is in. Its either a big 15mm or a small 25mm scale. In either case, it would be a nice addition to the table for a fantasy game.
Delta 7 Studios has a collection of free paper models of the Seven Wonders of the Ancient World: the Great Pyramid of Giza, Hanging Gardens of Babylon, Temple of Artemis, Statue of Zeus at Olympia, Mausoleum of Maussollos, Colossus of Rhodes and the Lighthouse of Alexandria.