Quick legibility hack for the Adafruit TIMESQUARE DIY watch kit: a couple layers of Kapton tape applied to the watch face make it less prone to washing out under bright light. The tape’s color is similar enough to the red LEDs that they shine through with little difficulty, while most ambient light is blocked.

Rubylith film (from a decent old-school art supply store) would probably work as well, if not better. But electronics types might already have the Kapton tape around.

(Sorry, doesn’t help you read binary.)