Theodore DeLand marketed the “X-Ray Deck,” 1907, which was a faked deck with a hole cut through one index. This was preceded by Clinton Burgess in 1904, with a card case with a rectangular hole cut from one corner, to allow the indices of cards to be read before they were removed from the face of the cased pack. This was published in Ellis Stanyon's Magic, Vol. 4 No. 5, Feb. 1904, p. 55, as “Novel Reading of Cards.”
Later card-case constructions by Clayton Rawson and Harlan Tarbell appear in The Tarbell Course in Magic, Volume 6, 1954, p. 87-89.