My choice of materials is likely to be different to most. I have a fascination with titanium, for no particular reason other than liking the appearance and weight.
My first experience of machining titanium was a commission from a friend: I mentioned to him that I fancied making something from titanium, in response to which he asked me to make him a wedding ring. My first attempt (which turned out to be too large) was in grade 5, the final ring was made from a piece of grade 2 bar.
Since then I have made another ring of my own design, holding two stones in a pair of tension settings.
For the watch, I have chosen to use grade 2 titanium for everything metal except the pinions and screws (which will be O1 steel) and the springs. So all wheels, plates and the case will be titanium. The screws will be steel as I think it is more suited to making fine threads than titanium.