I have printed a geocache pendant design (https://www.thingiverse.com/thing:3446444) several times to hold small items (e.g., vitamins for travel). 

I had two issues with the printed parts - the threads were often very tight and changing the barrel length was not straightforward.

This is a new design inspired by that pendant - not a remix. 

My experience is that the threads work easily straight off the printer. Also, the working interior length can be easily adjusted via the content_length parameter. 

The content_length is the length of the tube depth minus the threaded portion of the cap. The picture shown is a test print of cap and tube printed in copper PLA. In this instance the content_length was 10mm. The included STL file for the tube has a content_length of 43mm (my YubiKey is 42 mm long).

I printed the cap with threads up using brim and build-plate supports.