Quoted from RacingPin:These are thin clear vinyl disces of different diameters you can build up to minimize the cupping. It does work to stop the ball from getting stuck. You will see a slight ghost outline of each layer but that actually looks cool!
This is also undo-able if the next owner doesn't want it.
You could also get some mylar and some punches and do a similar technique (https://www.amazon.com/gp/product/B00OKS2K1A/ref=oh_aui_detailpage_o03_s00) .