LED membrane switch
21 pillow or dome embossed keys with metal domes inside,
Autotex F150 as graphic overlay,
3M 467 as rear adhesive.
Glue single or bi-color LEDs on silver circuitry for LED membrane switch.
LEDs come in a variety of colors such red, yellow, green.
The LED window area is generally clear or semi-transparent.
Usually emboss LED window to hold the LED inside.