In the context of the anime (My Dress-Up Darling), the "proper piece" referenced during Episode 2 typically refers to the Kashira (the head) of a Hina doll .
This episode focuses on the "proper" way to take measurements and the technical side of costume construction, which Gojo treats with the same reverence as his traditional Hina doll craftsmanship. Stai guardando SonoBisqueDollWaKoiWoSuru Ep 02 ...
If you are looking for the exact Italian title or translation often seen in streaming headers for this episode, it is typically: (Shall we hurry up?) In the context of the anime (My Dress-Up