How about gifting your dad a donation to his favorite charity on his behalf, or a volunteer shirt that he can wear while he's helping out? You could also consider signing him up for a volunteering event that he would enjoy or give him a book on how to improve his volunteering skills. Another idea is to get him a scrapbook where he can keep all of the memories and photos of his volunteering experiences.
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.