HELP! Gift ideas for a cellist.

hey reddit, i wanted to know if you could give me some suggestions on what i should get my boyfriend for our 6th month anniversary. he is in love with his cello, but sadly, i am a cello noob and i don't know where to begin in finding a suitable gift for my cello enthusiast. i want to get him something unique but at the same time, useful. i was wondering if there is anything that you would like to receive as a gift. i don't want to ask him what's on his cello wish list since i really want to surprise him. i am worried that if i ask him, he will figure out my plan. thanks.