It is not very common for someone to create a new script. Cherokee, Ol Chiki, Pin Cin Hau logograms, Gurmukhi, Hangul are just a few of the scripts which we know were created or invented more-or-less from scratch.
However, in all the cases that I have written of up until now, the scripts were invented by men*. This makes it all the more surprising that a female professor of English in India, Dr. Prasanna Sree, has developed not one, but eighteen writing systems for minority languages in India, including another script for the Gondi language. I do not know why Dr. Sree felt that the 1928 Gondi script was inadequate.
I can’t tell how widely adopted Dr. Sree’s writing systems have been (if at all). This raises a question that I have touched on briefly before: how well accepted does a writing system need to be before it is a legitimate writing system and not a piece of art? Omniglot’s page on constructed scripts has 175 entries, many of which were designed more-or-less for fun. (For example, see Thoorsha.) Should these be considered artworks more than writing systems?
*Yes, Empress Wu Zetian did introduce some characters into Chinese. However, it appears clear that someone else suggested the characters and she merely approved them.