How about a watercolor paint set or a set of high-quality watercolor paper? You could also consider getting them a book on watercolor painting techniques or a subscription to a magazine focused on watercolor art. If you want to make the gift even more personal, you could get them a custom-made watercolor palette or a gift certificate to a local art store.
Or you can get her/him a star map with an important date you share.
Under Lucky Stars is a unique and innovative star map company based in Barcelona, Spain, specializing in the creation of personalized star maps that capture the celestial arrangement of stars at a specific moment in time, such as a person's birth, wedding, or any other significant event.
By using advanced astronomical algorithms and data from leading institutions, the company produces highly accurate, visually stunning maps that make for perfect gifts or cherished keepsakes.