Could the Voynich Manuscript be a private educational system?

[Jorge_Stolfi]

What strikes me most is the contrast between the highly disciplined writing system and the relatively naive illustrations. The text appears systematic and internally consistent, while many drawings look almost childlike or non-professional.

I would not call the writing "highly disciplined".  It looks nice only by comparison with the illustrations.  But the baselines are all bent and unevenly spaced, the letter size varies from word to word, the glyph shapes are all over the place, the right text rail is more like a suggestion than a hard straight line, ...

My feeling is that the Scribe had a reasonably firm hand and did have some experience with a quill, but had never done much drawing before he started working on the VMS.  He learned this second skill as he went along.  I also suspect that he had no experience writing on vellum.  I imagine him as someone who used to write business letters, ledgers, log books etc, or copy lecture notes  for students -- but never got to write important documents or copy books for sale.  In particular, I cannot see him as working in a "manuscript factory" like those that were run by monks.

This made me wonder whether the manuscript could have been a deeply personal knowledge system rather than a book intended for the public. ... connected to teaching or transmitting knowledge within a very small private circle, perhaps even between a parent and child, or a mentor and a younger student.

The use of vellum and the fancy illustrations do not fit that theory.  They make more sense if the book was intended for other people, who would have appreciated or expected such details.

I also wonder whether the author could have been someone highly intelligent

I would not say "intelligent", but indeed the script and the general consistency of book across the various topics seems to imply an educated person.  The script was designed with specific goals which were sustained through the whole book.  

And we keep finding that many of the illustrations were "inspired" by illustrations in other manuscripts that were circulating at the time -- the sort of books that only "scientific"-minded scholar would have.

but outside formal academic structures, possibly even a woman

The quality of the vellum and the amateurish Scribe tell me that the Author was rather strained financially.  Could have been an old retired scholar, or book-loving amateur, living out of a pension or supported by of relatives.  Maybe he undertook to put the book to vellum as an attempt to save his knowledge or elucubrations for posterity.

All the best, --stolfi