To improve on the accuracy that can be achieved with a hand held die holder when threading custom pens or so called kitless pens on a lathe, and to eliminate the need to constantly drag the tailstock forward if using a fixed tailstock die holder, the smart way of doing it is with a sliding tailstock holder.
A sliding tailstock die holder holds the die firmly centred to the workpiece, and slides forward to advance the die as the length of the thread that you're cutting increases.
