Today the U.S. Patent and Trademark Office officially granted Apple a patent that relates to redesigns of Apple Watch and MacBook (primarily) wherein their current metal casing would be replaced with one mainly made of glass ("plastic, glass, carbon fiber, ceramic, or other materials"). The new design would also support close-to-invisible microperforations that form notification areas with interactive buttons. The patent also illustrates how this invention could apply to other devices such as an iPhone and Apple Pencil.  

Apple's patent FIG. 10C illustrated below depicts the sample MacBook having multiple illuminated input regions; FIGS. 3A-C illustrate examples of other illuminated symbols that could be presented.

Apple's patent FIG. 11D below illustrates a glass backed iPhone with illuminated areas for various icons and interactive buttons; FIG. 12C is an Apple Pencil with an area for illuminated icons and FIG. 13C representing a glass bodied Apple Watch.

Apple's patent FIG. 5D below depicts a top view of an opaque masking layer having an array of microperforations arranged in an offset-in configuration; FIG. 8A depicts a perspective view of a translucent layer that emits light having various properties at distinct viewing angles.

This is an extremely detailed patent. See Apple's granted patent 11,237,655 for more.