Adafruit Trellis is a great system for adding backlit keys to your own projects. Trellis’ elastomer keypad acts as both an input and fully addressable LED display. You can even tile multiple Trellises together to form large, captivating displays.
Now there’s a Python library to control Trellis from any computer with Python and I2C, like the Beaglebone Black or Raspberry Pi. Follow this guide for information on installing and using the Trellis python library.