[Stiglr]

For a building, it's a simple square or rectangular surface, with the 2S "two-sided" attribute applied to it. I use a separate material number for transparent materials, usually a grey, with 85 - 90% transparency applied to it. You *could* make it a (very) thin box if it's a thick glass, but I can't really see the point in doing so for most purposes. There's no need to apply any texture to it, unless, say you need it to be a pebbled glass, like for a shower enclosure door or other privacy glass. Of course, then, you likely wouldn't want it to be see-through anyway...

For my cockpit canopies, navigation lights and other irregularly shaped objects, I select the vertices from the object framing the glass, in counterclockwise order (such that normals will face outward), then Vertex/Create Ordered Surface. Then, use the same steps as above to assign it a glass material.