I just got an email from SilverTowne, announcing the introduction of a new silver round, made specifically for "stacking". I don't know whether this is a new concept, but the idea of using an interlocking design, to keep coins neatly stacked, seems like an interesting notion. These might also work well as high-stakes poker chips. http://www.silvertowne.com/p-24645-...mark-prospector-1oz-999-silver-medallion.aspx
Scottsdale Mint is doing the same thing: https://www.scottsdalesilver.com/store/product.php?productid=17558&cat=249&page=1 They're not up on the site yet, but they have some released into the wild on ebay I think: http://www.ebay.com/itm/100g-Silver...pt=US_Bullion_Bars_Rounds&hash=item541489fea1
I got that same email! I like them! I have a bunch of other stuff from, there quality is actually quite good for such a cheap premium!
Funny, the first thing I thought of were poker chips also. Interesting idea, not sure if it is for me though.