Probably, you are thinking of doing a kitless rollerball or a kitless fountain pen, altho' it could be a kitless ballpoint ... perhaps simpler in some ways.
Basic tools for RB or FP will include at least two tap and die sets ... one set for the cap-to-body threads ... one set for the section-to-body threads.
These tap and die sets are rather specialized ... not the sort of tools you can pick up at your local tool store.
Count on spending about $120 or more for these. . For a kitless ballpoint, only one set of tap/die, and local tool store might be able to help you.
It just so happens that there is a group of people on IAP who are now in the process of buying a variety of tap and die sets for making kitless pens.
Check out the "Group Buy" forums. . You could inquire from the IAP member who is coordinating this particular event (which is not a regular occurrence on IAP ... occurs about once every 1 to 2 years), or from the person who does the overseeing of all Group Buys ... I think his username is "Monty".
General advice ... get yourself thoroughly familiar with the process and decide what type and style of pen you want to make before buying anything. . If you don't do that, you could buy stuff that you won't need. . You have already seen some kitless pens that you like, so go over those very carefully ... pick one that you want to copy and talk to the person who made it about the tools they used.
Have fun!
