Minted metal coins require quite a bit of design and planning in order to encourage people to actually use them and to keep them from being easily counterfeited. The recent buzz over various cryptocurrencies makes real, physical currencies sound outdated, but what would you rather have in your pocket? (Sure, you can carry around a lot more cryptocurrency on a thumb drive, but would you really want to
?) Here are a few links on some new coins that you can collect and store in piggy bank.
If you'd like to read more awesome and interesting stuff, check out this unrelated (but not entirely random!) Techdirt post