Make it very simple, for this we need:
Keyboard, a small piece of org. glass, as well as LED, any color (I took blue)
Let's start - first we’ll unwind the keyboard and separate the necessary number of buttons that we need for the stand, the buttons also need to separate the legs, after that we will take care of the org. glass.
Saw off a piece of the required length, the shape can be absolutely arbitrary, then we begin to stick the buttons to the org. glass, ordinary glue holds them perfectly for a moment,
after you have glued the buttons, we will drill a small hole in the corner of our stand, into which we later paste the LED, now we will focus on the backlight itself, we will measure the output voltage using the voltmeter for the USB cable remaining on the keyboard, on the basis of this we will choose the LED that is suitable voltage, when everything is prepared, solder the LED to USB
and glue it into the hole that we drilled in the corner of the stand, that's all, we wait until the glue dries.
plug into any USB input and enjoy the result of work.