How about a nice pen and notebook? You could also consider a book on writing techniques or a course on creative writing. Alternatively, you could get him a subscription to a writing magazine or a membership to a writing group or online writing community that would allow him to connect with other writers and receive feedback on his work. For something more personalized, you could get him a custom-made leather-bound journal or a collection of vintage writing instruments.
Or you can get 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.