The glass where a coin dropped in the glass can be secretly and instantly extracted is an old and standard magic prop. This is an opaque stainless-steel version of the prop, (unbreakable, and maintenance free !) that will enable you to perform a novel Miser’s Dream effect or vanish a marked borrowed coin for re-production from another suitable prop.
Produce an endless supply of coins from thin air, and drop them into the glass, – the audience can see each coin drop, and hear it fall. Then dump them out or vanish them all.
Or have a marked borrowed coin dropped into the glass and reproduce it from someplace else. A very reasonably priced utility prop, which can be used under all performing conditions.
No coins included. Specially gimmicked metal cup like the classic “slot glass”