First, I should say this is a great design overall! Even though "ultimate" didn't work for me because I needed a spool adaptor for my 85mm spool holes from digistruct (which are admittedly ridiculously big), I really appreciate the thoroughness of the design with all the different connection options. I'm planning to use the 2020 ExAl connection, if I can get that sloped button surface to print right...
About the volume trimmed parts, this is a big section of your details:
"3D-print only what you need while testing!
As you already realise this image is not the entire filament spool stand (http://www.thingiverse.com/thing:508896). It shows a crucial part and best-practice related to 3D-printing.
Therefore we cut away the smallest possible volume surrounding the fittings and 3D-printed them in a fraction of the time which otherwise would have taken hours and hours to find out."
It would be nice if you gave us an STL of all the "smallest possible volume surrounding the fittings" parts so we can test their fit on our printers rather than every one of us having to redo this cutting.