> Is the constant-diameter property actually relevant to vending machines? It seems to me that unless you're trying to fit the coin down a "tunnel" of absolutel

> Is the constant-diameter property actually relevant to vending machines? It seems to me that unless you're trying to fit the coin down a "tunnel" of absolutely minimal size A lot of cheap coin-op mechanisms put coins through an exactly sized tunnel as first step, so while it's probably not critical, it would be nice to have the coins be constant diameter as now you either need to configure your coin acceptor to be more slack or install a new one altogether.