The 1,000 banknote from Maldives is considered to be one of the most beautiful of all currencies
(lemmy.world)
Why, because they tear a giant hole in your pocket with the weight so you know you have no coins in there? ;)
Japan made all their coins identifiable by touch as well. There's a small and big one, then for the 4 with similar sizes 2 have milled edges and 2 have holes.