Today the U.S. Patent and Trademark Office officially granted Apple a patent that relates to AirPods Max described as having glass earcups. Either Apple wants to make the next generation of AirPods Max lighter by introducing a strengthened glass earcup or Apple passed on glass earcups in favor of the anodized aluminum cups we have today.  One of the big criticisms of the AirPods Max was the weight. Using glass would definitely make them lighter. To ensure that the glass doesn't crack easily in a drop incident, Apple's patent describes using an asymmetrical chemical strengthening process for the glass.

Apple's granted patent covers various techniques for improving the drop performance of an earphone, in particular along the edge of the earphone's glass earcup.  In accordance with some embodiments, an earpiece includes a glass earcup having an outer exposed surface, an inner surface, and an edge extending around the perimeter of the glass earcup. The earpiece further includes an upper enclosure to which the glass earcup is laminated, and a protective coating lining the edge of the glass earcup.

Apple's patent FIGS. 4A-4B below show a technique for improving the drop performance of the glass earcup by extending the earpiece textile up to the edge of the glass earcup; FIG. 9 is a flow chart showing the steps of the asymmetrical chemical strengthening process used in treating the glass earcup.

For finer details, review Apple's granted patent 10,924,836.