The Coaster by Terry Chou

Penetration, the seamless passage of one solid object through another, ranks among magicians' most cherished magic effects. Within the realm of Penetration effects, the Coin Through Cup, owing to its use of everyday items, has secured a special place in magicians' hearts.

Although numerous ideas exist for this effect, concealing the gimmick within a coaster stands out as a popular solution. However, many coasters available might raise audience suspicions due to their unusual appearance, excessive sleight of hand, or the presence of peculiar bulges.