A simple watercolor palette with 60 wells in a ~5"x7" space.
This also fits within these tins very well, if you prefer a snap-to-close lid: https://www.amazon.com/Pack-Container-Large-7-25-Crafftin/dp/B076TJ75KT
This works fine printed in .3mm draft mode. Make sure you're not underextruding, or it won't be water-tight, which would be bad.
The author hasn't provided the model origin yet.