(Edited Sep 19 to add definition of "Nickel" as used in the drill
Thank you Patrice for pointing out the need for clarification.)
Try this sometime
Swing drill by way of Michelle Mullen (spelling), met her, was coached by her when she held a seminar at ASU.
You will need a nickel and dry hands
Place the nickel in the palm of your hand, keep the hand OPEN, place and swing it, do not lose the nickel.
You can not grab it. Centrifugal force will keep it on your hand, this can also foster good arm position as if you roll the forearm, the nickel will slide.
Nickel (United States coin) - Wikipedia
nickel coin weight from en.wikipedia.org
A nickel, in American usage, is a five-cent coin struck by the United States Mint. Composed of 75% copper and 25% nickel, the piece has been issued since 1866. Its diameter is .835 inches (21.21 mm) and its thickness is .077 inches ( 1.95 ...
Diameter: 21.21 mm (0.835 in) except Shield nickels (1866–1883) 20.5 mm (0.807 in)
Mass: 5.000 g
Years of minting: 1866 – present (except 1922, 1932, and 1933)
Silver: 1942 to 1945 Wartime Nickels only (with large mint mark on reverse) 0.05626 ...