How about getting your grandpa a robotic arm kit that he can assemble and experiment with? Another idea could be a book on the history and evolution of robotics, or a subscription to a popular robotics magazine. You could also consider getting him tickets to a robotics convention or expo in your area where he can learn about the latest advancements in the field and interact with other enthusiasts.
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.