Fountain pen cap (top part only)

This is a cap for my old Pelikan fountain pen that I bought around 1984, damaged about 2 years later, forgot about it and resurrected it a few years ago. I tried to glue the broken parts, but that did not work long. 
The reengineered cap parts I put together without glue. The outside cap itself is printed a little bit smaller than the inside cap. I put all parts together without the outside cap and put them into the freezer. The approximately 40 K temperature difference between the parts let me put the outside (warm) cap on the (cold) inside cap. Once both have the same temperature they hold without any glue. 
 

The second image shows all parts together, I  printed the outer cap (bottom left) again in black (that I used CPE has no specific reason, it's just that I had it in and it's black). 
The silvery thick cap on the image is just an intermediate version without any inner parts. I abandoned this one, because the clip could not be fit in (and then the thing always rolls away).