The book "Conrad, or the Tin Can Boy" by Christina Neutlinger

Mrs. Bartolotti lives alone in her house full of useless things and only sees the pharmacist Mr. Egon two days a week. When she receives her son Konrad in the mail in a tin box, she almost faints with surprise. But the boy is incredibly smart and clever, and Mrs. Bartolotti immediately decides to be a good mother. And what to do when strange people in blue clothes appear for Konrad? This humorous story by Christina Nostlinger reveals the modern relationship between parents and children.