The deck shell is described in the Asti Manuscript, c. 1670-1730, p. 97 of the Pieper translation, as a method to hide livestock. This manuscript was translated in Gibecière, Vol.8 No.1, Winter 2013, p. 29-234. The centers of the cards were cut out, and then the deck was sewn together. A cover card was glued on top to make the deck seem normal. The internal cavity was used to hide loads that the magician could produce.
A deck switch using a Card Case Shell was published by Stanley Collins in his trick “The Flying Sum and Divining Cards” in Will Goldston's The Magician Monthly, Vol. 9 No. 8, July 1913, p. 124. The shell is openly transferred from one deck to another in an off-beat moment. See also Deck Switch with Shell.