When I was small, I remember there being a regular children's magazine coming into our hose, and that included a "Bastelbogen" on the center pages (at least some of them did). So you could cut out and glue together a little house, or something else. They'd quite often find their way onto the train scenery that came downstairs from the attic around Christmas time. (I think the scale more or less fit, but frankly I didn't really care. The important thing was that I'd get to cut and fold and glue and then have a little something to put there.)
Later on, I once made a large cardboard castle... which then stood on top of a cupboard for ages, getting a little messed up and dusty and deteriorating a bit over time. These days, I usually pass when given the chance to buy one - I still like the idea very much, and I'd enjoy the making, but then I never know what to do with the models. (I guess one could glue them to the ceiling and make an upside-down landscape there?) In case you also have a liking for those lightweight mini buildings, and don't mind having them stand around then, you might want to take a look at the Schreiber-Bogen website or, to be precise, their English shop. I've linked you straight to the churches, but there's also houses, ships, and whatnot.
Me, I always get a little nostalgic seeing these paper model sheets. One day, though, when I have too much time...