I would say if it had TWO taps that would be okay (not being disagreeable Mark!) A 'first' tap makes starting a thread easy, a 'second' tap cuts the thread to a more defined end, a 'third' or 'plug' tap is only used in blind holes to take the thread all the way to the end of the hole. For pen-making I can't really see you needing a plug tap - am I wrong?
To be honest my set has first and second taps but since I only tap soft materials I only ever use the second tap. Maybe that's all you need?
In case anyone was wondering, a single die has both first and second threading capability simply by reversing the die in the holder. A neat trick for cutting male threads tight up to a shoulder.
