道具 are private, reflecting the
茶人's taste (→ 好み)and aspiration.
A tea devotee will not reveal to others what kind of tea utensils he has in his private collection. At a tea gathering, an event based on the principle of //一期一会, the element of suspense as to what utensils will be used is essential.// (Hatakeyama Issei. Funnily, his collection ended up in a museum)