W. H. J Shaw described a novel method to vanish a coin, titled “The Dissolving Half Dollar”, in Magic Up to Date; or, Shaw's Magical Instructor, 1896, p. 61. It required a dummy coin, made by pressing tin foil against the half dollar to create a fragile shell. This shell would be passed off as a regular coin. To effect the vanish, the magician would simply crush the foil into a small ball, allowing for a much easier concealment.
This idea has been reinvented multiple times, including in The Conjuring Record, Vol. 1 No. 4, June 14th 1913, p. 4, and more recently by Nathan Kranzo in Squish and Other Mysteries, 2006, np.
The same prop was also used in a different context. The foil shell was used openly and explicitly as part of a coin change, titled “The Fragile Coin”, anonymously contributed to The Wizards Annual, 1913, np.
Around 1987, Robert Frederico used a fake half dollar made of head and tail foil impressions to fabricate a lightweight coin that could be levitated by invisible thread: "The Ultimate Floating Half-Dollar"; see ad in Genii, Vol. 51 No. 9, March 1988, p. 582. Frederico released a self-published booklet called Disposable Coins for guests of the 1987 New York Magic Symposium, containing ideas using foil coins.