Working on converting a 12'x8'x8' room in my garage into a control room. This room has 2 exterior walls, one of which includes a 42" square window. The exterior walls will have 5.5" insulation and 5/8" drywall on isolation clips and hat track. I did some reading here and more or less know how I want to approach the window itself, and felt like documenting the project so this is the beginning of that.
I went to a local glass shop to get a quote, for a few varieties of glass, and found it to be out of my price range. Luckily for me, 40" square glass top coffee tables are fairly common and I was able to get 2 locally from different sellers, for $100 total. One with a 5/16" top and one with a 1/2" top. They've got some scratches, but this doesn't require perfection as it's mostly for natural light less for observation. Both panes are tempered and beveled, though the bevel will likely be hidden when all is said and done.
The plan is to mount the thicker pane in a new sash and mount it in the existing hole. The interior pane will be mounted in a decoupled frame built on some added lumber behind the drywall for reinforcement, attached to the back of the hat-track. When I get to actually building it, I'll include pictures.