This is an adapter ring for the CoreOne+ spool holder.

When I used a little 250g filament spool on the CoreOne the first time I noticed a significant tilting of the spool when printing caused by the gap of the spool holder. With the usual 1kg spools this isn't an issue but with the small ones it can be annoying.

Well. I made this model to fill the gap on the holder and thus avoiding tilting when using small filament spools (like those little 250g spools).
This is my very first addon for the CoreOne printer. It is made using OpenSCAD and I include the source file too (for those who like to modify it or for those who are just curious).

I recommend printing it with PETG. 0.2mm layer height should be sufficient.

Enjoy.