Been having a lot of fun with 3D CAD design and 3D printing lately and after MANY hours of trial and error I have come up with a mod that I'm pretty happy with.
The mod consists of 3 separately printed pieces (base, curtains, and insert) where the curtains are screwed onto the base with 3 tiny screws, and a snap-in removable insert. An LED strip provides the lighting to the band and a #89 socket is mounted to the bottom with a flasher LED installed to light up the insert. I used one of those LED controllers that are in just about everything these days to control the LED's and the remote control is convenient for changing the pattern. I designed and built a special plug-n-play control circuit on a pcb that fits between the connector that goes to the band solenoid. The circuit senses when the band starts moving and turns on the light show over the band that stays on during multi-ball and then turns off once multi-ball ends and the band stops.
See it in action here:
Lot's of fun!