Adapter: Cross Slim to Uni Signo UMR-85

I present my pen refill adapter, for use in pens that take the Cross Selectip and Slim ballpoint and gel refills. It allows such pens to use the Uni Signo UMR-85 refills instead (not included).
This model contains 8 adapters, attached together with sprues, which will need to be separated using a craft knife.
The Cross Selectip refills are around 111mm long and 6.4mm in diameter. The Cross Slim refills are around 102mm long and 5.6mm in diameter. The Uni Signi UMR-85 refill is around 111mm long and 6.1mm in diameter.

Depending on what refill the Signo refill is replacing, it's plastic tubed body will need to be trimmed to the required length, minus the thickness of the adapter's base.
Some Cross pen have a spring in the tail of the pen, which the base of the refill sits on. This adapter creates a flat base for the Signo refill, so the spring can press against it evenly and not fall into the refill's tube, which would happen otherwise.

All Uni Signo refills that start with an eight can be used, so all these refills are dimensionally the same as the UMR-85N (0.5mm tip):
UMR-82 (0.28mm tip),
UMR-83 (0.38mm tip),
UMR-87 (0.7mm tip),
UMR-80 (1.0mm tip).

The adapter needs to be printed in the polished white or coloured plastics, as the smooth polished finish is functionally desirable.

Due to the very varied nature of pen design, I cannot guarantee that this adapter will work with any specific pen, although I've made every effort to make it as universal as possible.

I plan to make as many refill types compatible with as many host pens as possible, so If you have any suggestions on refill adapters, please let me know and I can hopefully make it available, depending on the relative sizes involved. I have now created dimensioned drawings of over 80 standard and obscure ballpoint, gel and rollerball refill types, so I like to think that I have a fair idea of what is and isn't possible.