I present my multiple refill adapter model. It contains 5 adapters which will allow Mini/Multi D1 refills (not included)to be used in pens that take these gel refills:
Pilot Mini G2,
Pilot Hi-Tec C,
Stabilo Easy Gel.
The D1 refill is around 67mm long and 2.3mm in diameter.
For details about a specific adapter, please see the individual listing for it on my Shapeways shop page.
I appreciate that the D1 refill is generally a less practical refill, compared to most of these refills, in terms of ink volume. However, many of these refills are propriatary, so this adapter exists to hopefully provide flexibility, between your favourite pens and refills.
The adapters needs to be printed in the polished white or coloured plastics, as the smooth polished finish is functionally desirable. The D1 refill is held in place, by the adapter, using friction. The holes around the side of the adapters are present to help with the removal of unbonded plastic powder from the core, when being polished. However, some powder may still need to be removed, with a pin or thin metal rod, before inserting the refill.
The adapters will need to be separated from each other using a sharp craft knife or zero angle side cutters. The sprues will need to be removed and the points where they connect to the adapters smoothed flat.
Due to the very varied nature of pen design, I cannot guarantee that the adapters will work with any specific pen, although I've made every effort to make them 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.