Making use of thick walled glass (which it should be since you are tossing coins in rather aggressively for the sound) and 12 half dollar size 31.5 mm token coins from Abbott's.

With this you will be able to pick up the glass and start producing coins one after another from thin air dropping them in the glass where they are heard clearly to arrive and this can be done for whatever period of time desired until the audience knows you must certainly have a glass full of coins a true Miser's Dream. Includes illustrated instructions.