To be honest, it depends on your design... I would try to find some some tack-buttons ( really small) that are easily pressed, cause larger ones are usually quite hard to engage, esspecially if your expecting to have a coin fall on them. Like u said, it depends on design, do you have one in mind already? I can post one on here 2morrow (on iphone, can't post images) that would register all coins (penny, dime, nickel and quarter) if you wish.