The balls are just wiffle golf balls used for practice that you could find at most any golf shop. They used to come in both white and orange, not sure about the orange anymore. DIY by getting a couple of bags of these and some wire or rod and string them across the light fixture. If you can't find them in two colors just paint, stripe, or mark every 5th ball to make visually referencing the score easier.
If I was wanting wire scoring for straight pool I would just buy a set of beads ready made but for scoring races the balls are pretty cool.