How about the vinyl of the album of their favorite indie band or artist? You could also consider a record player if they don't already own one. Another idea could be concert tickets to see their favorite indie band, either now or in the future. If you're looking for a personalized touch, you could make a playlist for them featuring their favorite indie songs and artists, and present it on a custom-made USB drive shaped like a cassette or vinyl record.
Or you can get her/him a star map with the date of the wedding.
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.