The multiple-sandwich plot pre-dates Roy Walton's neo-classic routine, “The Collectors.” In O.W. Meyer’s “The Burglars” from Jean Hugard's More Card Manipulations Series 1, 1938, p. 17, four Kings trap three selections. The difference is that the Kings are face down.

Walton's use of face-up collector cards heightens the clarity tremendously. His original routine, “The Collectors” appeared in Abracadabra, Vol. 47 No. 1203, Feb. 1969, p. 99. Ed Marlo, later that year, in The Hierophant, No. 2 (Winter), 1969, p. 155 of the combined collection, expanded the effect from three Kings catching two cards (Joker and a selection) to four Aces catching three selections. In Pabular, Vol. 1 No. 3, Nov. 1974, p. 28, Alex Elmsley contributed his “One at a Time Collectors” variant.

• For later handlings, see the Category in Denis Behr's "Conjuring Archive"