Track bikes use 15mm nuts to secure the wheels as all tracks I've ever been on QR is not allowed.
I think your friend might appreciate a high-end 15mm wrench from Rene Herse.
It has a beautiful finish, looks and feels really nice and it's not too outrageously priced for a gift. Campagnolo has a similar one but it's nearly two times this price. Both of these can also be used for spreading peanut butter.
https://www.renehersecycles.com/shop...-crank-wrench/
It says 'crank wrench' but it in fact a 15mm wrench that will work on all 15mm nuts and bolts.
If you're super nerdy here's a little article on some other nice 15mm wrenches
https://www.bikeradar.com/features/t...-great-beauty/