Dying PBT Keycaps

I just got my /dev/tty blanks in from Massdrop and I an thinking of dying them to match my current ABS colorway.

I have looked at the guide and I think I am able to do all that, but I am wondering what kind of look I am going to/can get by dying the gray and red caps?

I assume the gray caps would just yield a slightly darker color, but I am curious if I can get an interesting shade of brown by dying the red keycaps with some other color (or just more brown?)

Any hints on dying the colored caps or dying PBT in general are appreciated.