The Amazon Echo Wall Clock has no front "glass" yet does have a warning about dire consequences of touching the hands. It's also open (literally) to collecting dust, debris, and who-knows-what in our kitchen. My solution was to add an inexpensive (£5 from a well known auction site) perspex "glass" with a 3D printed bezel.

The front diameter is 250mm - too big for my Ender 3 Pro to print in one piece, so I separated it into 3 sections. Each has an overlapping extension to connect to the next, so each print is actually slightly longer than a 120-degree arc.

Each arc is constructed as a main length of 116 deg, extended by a 4-degree section grooved on the inside, to accept a 3-degree tongue extension from the inner surface of the opposite end. These have built-in support for the tongue, easily trimmed away after printing. A tiny amount of material may need to be removed from the overhanging part of the groove, if there's slump in the bridging. The angle between the front and side faces is slightly more than 90 degrees: 92.5 degrees as closely as I can measure. The perspex I used is 2mm thick.

Print at 0.2mm layer height with no additional supports; I used 3DWarHorse white PLA.

I glued the three pieces together with Loctite Superglue Gel and then fitted the bezel over the perspex and the clock front, securing with three M3 countersunk stainless steel screws.