Look, economically speaking, if you tried hard enough you could standardize a new currency, it'd have to be in "physical" items but it could be done. It's something that I'd love to see people try and do, but it takes work and a lot of upkeep. Afterall, you have to prove that your currency is worth more than the item it's made of and have a method to prevent people, other than yourself, from minting new currency.