Cool. Did something similar using a LED light bar strip that is narrow and fits within a long 1/4" aluminum U-Channel. Kind of hard to tell from the pic but is sandwiched between upper tier stand and keyboard.
EDIT: fixed an issue with pic.
Nice, I made 2 versions already, but I think I'd design it around a squarish U shaped channel if I were to do it over a third time. Despite the extra pieces the round pipe has the unintended benefit that it can be rotated easily for different tilts. Might try a universal version for other keyboards that mounts on a stand or something. The LED strips work with synths nicely, being a narrow, long section of knobs to light up.
Pulled back from making it a mega project, but was daydreaming about using an arduino to change the colors of the strip, from the midi CC's of the knob positions. Like a color organ, but it would react to the knob positions. Or have the color change from program change messages, like each patch has a color.