Machinist sounds extreme easy to say Dexterity, but what else could we use and what sounds fun; I am currently ruling out Strength.

My top choices is Piety and Intelligence, Then_____ ... I leave that as option Echo.

Ok Piety, Let start with the two biggest option, We really don't have a piety build, now if the 3.0's healer is, I'm ok, but we could change SMN to Piety, but thats a big issues in-its-self.(I left my Ten foot pole outside)

I envision Machinist like a speed caster, where the more piety the more powers stacked into the bullet. Think about XIII and how you had to cookie-cut your ability. XFire bullet or XThunder bullets uses X amount of MP; the More MP is stacked in XT^x or XF^x kind of like a cocktail of potency. We can always make a minor adjustment to Piety that only affect but lets try to avoid the Dump-truck method of creation.