Electronics: PIC 16F690 microcontroller and DS3231 RTC with battery backup, driving a multiplexed display of approximately 34 flat-top white LEDs with wide angle dispersion. (1-2 LEDs per word.)
Face is adhesive sign vinyl affixed to the back of 1/8" clear acrylic. The baffles are whatever thin strips I had on hand, and the whole thing is encased in a low-profile 12x12" frame.
Inspired by this great clock. There are now numerous others on the internet including this one, and this one.