What would be a nice gift to a painter?

I'm planning a farewell gift for my English teacher. Although he has a passion for books, he has also been an artist all his life. He might not be a professional painter, but his paintings that hang in our school corridor are really colorful and amazing. Since all the other teachers plan to gift him some book, we students decided to try our luck with something related to painting. Unfortunately, none of us have any idea on how to go about it (the closest we came to a painting was drawing the national flag on independence day). Requesting suggestions for what could be bought for him that would allow him to continue painting?