After having seen a post on r/NovelAI about how a violin looked weird when used in a prompt I decided to try out an experiment to see which instruments may actually work.In total I tried 966 different instrument from Wikipedias list of instruments together with the exact same settings in terms of seed, scale steps and options.
I generated all of these in one big batch over the course of a few hours. I chose the prompt based on what would yield a picture that was exact enough to be repeatable, but still not influence the instruments too much.
Portrait of a beautiful woman playing a {{{{{XXXXXX}}}}}, on a stage, realism, blue eyes, ginger hair in a pixie cut, small breasts, jeans and t-shirt with print, full body
Model used is NAI Diffusion Anime (Full), Steps 28, Scale 11, Quality Tags On, Seed 1156267442, Undesired Content Low Quality + Bad Anatomy.
Over all, NovelAI currently struggles a lot with props in general, which is very visible here. Including that the subject is playing an instrument, even when blank, seems to lower the quality quite a lot in terms of facial features. This also highlights a lot of problems that occur with fingers, hands and anatomy. The AI seems to have a general sense for where an instrument go on the body, but not quite how to use it once it is there, giving some of the instruments a feel like it has just been attached to the body, rather than being used by the person.