I thought about all these mechanisms before and I came to the conclusion there is no way to have decentralized physical backing for a crypto-coin.
Inside the GEC economy, anyone may spend entire
exacoins to themselves at
anytime; however, to do so would be to make everyone quintillion-aires, for others would soon follow suit. (In other words, it is the reality of others' "following suit" that, ultimately, regulates the inflation of the GEC economy.)