How about a Mozart music box that plays some of their favorite Mozart pieces? You could also consider a book about Mozart's life or a set of his complete works. Another idea is to purchase concert tickets for an upcoming performance of a Mozart symphony or opera near your friend's area. If you want to go for something more sentimental, you could put together a photo album of your friend's favorite Mozart concerts or performances they have been to.
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.