How about a high-quality, leather-bound journal or sketchbook? You could even get it personalized with his initials or a meaningful quote. You could also consider getting him some specialty pens or pencils, such as waterproof or archival ink pens, that are perfect for outdoor use. Another idea is to take him on a nature-themed adventure trip or hike, and gift him some photography or art supplies to capture his experiences in his journal.
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.