Created test labels for the annunciator panel using an Avery clear label kit. I found that the easiest font for me to read from two feet away (normal viewing distance) is Franklin Gothic Demi, all capitals, 15-point size. We'll see how it looks once I print it on a colored label and backlight it with a white LED.
I made these prototype labels to check the font, letter spacing and text size for my annunciator.
