As a kid I had green #90 button, very close in size to an LW lens and nearly the same green plastic, but an LW lens doesn't fit right in a #90, so it was a green#90(or other #90 clone; like the one with a thermal breaker) pretty sure it came with my LSA/Mercury X-set; which had a few other one-off items included.
Anyhow, if you ever do a #90 replacement button, let me know if a green might be a possibility. (I usually used it and a red #90 for turnout control. I still knock the lever type around sometimes....what an old spaz )