How about getting him tickets to see one of his favorite live musicians or bands? You could also consider going above and beyond by purchasing VIP tickets or a backstage pass to make the experience even more memorable. Another idea could be to create a personalized concert package that includes things like a concert t-shirt, hat, or other fun merchandise from the event. Additionally, you could make a DIY scrapbook or photo album of all the concerts/events you've attended together.
Or you can get him a star map with the date when he was born.
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.