Will (darkzero) does the best full profile knurling I've ever seen on Ti-6-4. He's the person I'd contact for a one off.
Bands are more easily knurled but I have never found a way to make them either full profile or uniform:
Adding a knurl detail like that to an existing light isn't hard to do, as long as the body is a straight cylinder with enough thickness that grooves can be cut at least .016" (0.4mm) deep.