Using real glass can add another level of realism to your models, however, real glass can be really difficult to cut.
In the past, I’ve read about using a carbide scratch awl or a diamond point scratch awl to make cuts in glass. I tried a carbide tip awl and destroyed some of the glass. I have also tried to use a diamond tipped awl but are way too expensive. I did more searching online and found a thread that suggested using a Dremel cutoff disc to score the surface. It worked like a charm and I haven’t looked back since.
First, you must to use a hard surface otherwise the glass will break. A modelers mat or cutting mat will not work very well because the surface will give and could break the glass. I use a Plexiglas cutting board which I use for my photoetch parts. I use a clear Plexiglas holder that is transparent so I can see the size I am cutting. I purchased both from eBay.
After scoring the piece of glass, I hold it on the edge of my Plexiglas base and holder along the scribed line and lightly tap it with my tweezers. It will usually fall off on a clean break. It does take a bit of practice though.
My measurements are not exact but extremely close to size. You can’t get too accurate because the glass doesn’t always break or cut correctly and the disk is not real fine.
I use a product called Stix to lift the delicate piece of glass into place. It does take some practice but works well.
I use Superglue to secure the window and then attach the rest of the window trim to conceal and secure the glass.