What's the best way to make a new one?
Luciano.

Hi Luciano,

This is one of those questions where the answer starts with it depends...... it depends on for which pen the inner cap is to fit for start, many of the older flat top style pens used straight forward sleeves of hard rubber, some even used a wood plug of a suitable length and tight fit which was then drilled to a clearance fit for the nib. I have even found the ends of older RHR eye dropper type barrels used as inner caps on some Mabie Todd pens from the early 30s.

Some companies threaded the entire length of the inside of the cap and threaded the outside of the inner and screwed it into place, this makes things a bit more complicated and it is easier, unless one has a lathe and can cut a suitable thread, to find one from a donor pen of the same type.

Then there are other pens where the inner is part of the main cap or for other reasons it is easier to find a replacement cap unless you have the facilities to machine one from scratch or adapt another to do the job

A little more information about which make and model of pen you are trying to fix would help someone to give a more specific anwer to your question.

Sorry not to of more help.

Cheers, John