Atari Repair Parts now has stock of replacement keypad overlays for Intellivision 1 and 2 controllers. The price is $3 for one, $5 for two and $25 for a 12-pack. The store also has stock of quite a few items Atari and Intellivision owners might be interested in, so I suggest scrolling through and seeing if there’s anything else you’d need:
Purchase Here: https://atarirepairparts.com/#!/Other-Parts/c/160952147
I’ve owned a few Intellivision consoles since starting RetroRGB and most were missing the overlays. I never took the time to search out replacements, but saw Leon’s post about these and figured I’d share. I haven’t personally tried them and there might be other alternatives, but at $3 each, these seem like an excellent place to start!