If you were lucky enough to live before Legos were a big thing, you probably had a building set called "Block City." Those of us who had them both always preferred Block City! Block City is no longer manufactured, but there are still sets to be found and many ardent collectors of them! Since I got my first 3D printer, I've been making additional parts for these sets, and will be posting a few of them. Here is a collection of "modern" windows, including one-piece corner windows that fit a lot better, and are way easier to build with, than the two-piecers that come with the sets. Sometimes there is too-tight problem when you put two or more of these together. This is from the slight bumps in the corner. Simply sand them smooth for a perfect fit! Enjoy!