There are many kilt accessories.
And of course, the most traditional accessory is the "sporran," or pouch worn in front of the kilt. These can be made of leather, hair on hide, fur, or any combination thereof...with or without tassels. Many include elaborate silver work featuring Celtic knots or designs. Sporrans, of course, come in handy since kilts have no pockets! When I wear my kilt, my wallet, keys, and cellphone go in my sporran.