There are frame/bike makers who work with various materials and some who work with one or two and other who work with just one. When I was shopping for a Ti frame in 2011 I focused on those who specialized in titanium, and there are a number who have already been mentioned here and some who have not. If you are looking for the top class in Ti frame builders I would add to the list Steve Potts (incredible precision and knowledge of ti frame building), Crisp (he works out of Italy, but if you want the top class add him to the list) and although he works in steel as well as Ti, Mike Desalvo is among the most underrated ti frame builders. I chose Bill Holland and have an exogrid frame that makes me happy every time I ride it, look at it, or think about it. Friends ask me what frame I want next and I cannot think of an answer......... I am that happy