Here was my routine for 15 yrs for what its worth
Produced and drank a full glass of water from the EGYPTIAN WATER BOX ( remember that one?)( also drinking some water during a performance can be recommended) Fingerpalmed 2 silver dollars in right hand, and held the glass with the fingers inserted. Produced a dollar with left hand ( Im left handed) and did a mini misers dream until the 3 dollars were produced. Had the dollars signed and did coins to pocket as per Bobo, handing the coins to the spectator to verify they are the signed ones. I then cover the glass with a hanky, and instruct the spectator that when Ive counted to 3, h/she must throw all 3 coins towards the glass, from where they will penetrate the hankey and land in the glass.
I pick up the glass ( hanky has a circle disc sewn into its centre) but not before vanishing it into the table well. Carry it forward, count 1, and on the count of 2 flick it away showing glass disappeared.
Finally this is an effect defenitely worthwhile considering ESPECIALLY if youre gonna get a new jacket anyway.