The FW3A has no built-in trit slots on the outside of the body. However, it can use a Carclo 10507 optic, and I know that Neal is selling such optics with 3 trits pre-installed for $30 each.

Some people have also modded the tailcaps in their aluminum FW3As to add room for a trit. That’s probably the only other place to put one.

If bezel trits aren’t bright enough for you, Lexel has prototyped an aux led board. When installed, you get a colorful glow behind the bezel when the light is off from 12 tiny colored LEDs. These are typically much brighter than any trit.