Also called the Chop Chop Cup, this magnetically gimmicked cup is credited to Al Wheatley, who performed under the name Chop Chop. He invented this cup no later than 1955, and it quickly became a popular dealer item. However, the central concept of gimmicking a cup to temporarily hold a ball secretly inside it has a long history.
The idea of applying a sticky substance to the interior of a cup, to which a ball can be secretly adhered was recorded in France in the 1723 revised edition of Jacques Ozanam's Récréations mathématiques et physiques; see the Pieper English-language translation in Gibecière, Vol. 6 No. 1, Winter 2011, p. 97. Forty-one years after Ozanam, in Japan, Hirase Hose described the same idea in Hokasen, 1764; see the Sherer English-language translation in Genii, Vol. 79 No. 5, May 2016, p. 73. In both sources, this method was incorporated into Cups and Balls routines. Hose explains that the adhering ball was dislodged by striking the inverted tea cup with the magician's fan. Much of the old magic of Japan was imported from China, so this idea could have been used there years earlier. Whether the idea of the sticky bowl traveled from the West to the Far East, or vice versa, or whether it was independently derived, remains an open question.
In the early 1700s Matthias (or Matthew) Buchinger's Cups and Balls routine was reported by W. Griffith, in his Whole Art of Legerdemain, in Perfection (the date of the earliest edition estimated to be the late 1720s-1730s). Griffith says that Buchinger gimmicked one of the cups for his Cups and Balls routine in this way: “you must have a Tin Bottom, sawder’d in it like a Grater”. When a cork ball was placed onto another inverted cup and covered with the gimmicked cup, the prongs of the “grater” would impale the ball and pick it up when the upper cup was lifted. By setting the cup down somewhat sharply on the table, the ball was dislodged.
Given magicians' long love of magnetism as a secret method, it is surprising that it apparently wasn't applied earlier to replace adherents and prongs as a method of retaining and later releasing a ball inside a cup. Chris Wasshuber points out a precursor to the magnetic Chop Cup, in the form of a Ball Vase. This is described in Magic No Mystery by Wiljalba Frikell, 1876. The trick, titled “The Magic Dutch Balls”, is there attributed to M. Courtois (stage name of Joseph Grandsart), a French-Belgian magician. The magnetic lid of the vase was deep enough to pick up and hide a ball placed into the base of the vase, and the ball could be dislodged from the lid with a rap, just as Al Wheatley did with his Chop Cup.