After about five and a half years, the OEM shift indicator in my rear SRAM Grip Shift failed, so I replaced it with a piece of right-angle polypropylene backed with hot pink vinyl:

All done by hand, because it’s easy.
I’d used up my stock of genuine replacement indicators long ago, but they’re now down to two bucks (probably because Grip Shifters are obsolete) and I’ve stocked up in anticipation of future need.
Let’s see how long this one lasts …