One thing to note, you only really want to scribe the glas once. You do not need to scratch it with the file over and over. the imperfections of multiple scribes made tiny cracks. Also, it may not have needed so much heat.
I have a security camera that I need to mount outdoors and wanted it protected from the elements. It did not quite fit in the lip of this jar so I cut the top off so it is wide enough (and still tall enough) to accommodate the camera.