I used to make small nozzles out of nickel tubing, it as drilled way oversize and then rotary formed using a ruby to "clse up" the end.. a carefull setup and a chase with the apropriate drill works..

I also made custom pen tubes using a spin forming technique.. a turn tool wth a "bald" bump kurl mounted at an angle to the spindle CL and a small wire in the drill quill to maintain the ID.. the pin was turned out of drill rod then flamed quick and dirty (only made these 2 dozen at a time).. get the slimeyest goopy oil you can find (100 weight+) slop it on there insert the ID mandrel and form the OD and ID from the cross slide.... the bald knurl can be substituted for a nice polished chunk of carbide or something else suitably hard (I have hijacked the dressing diamond from the surface grinder in a pinch)

just keep the chuck length short, even think about using x nose collets for this one

I also had ruby forming tools made.. trying to find those