Layers of concrete and abrasive resistant plate (AR plate) might be a start for home vaults, but I haven’t bothered to design anything, yet (e.g., bolts/latches).
Banks are getting ready for a repudiation of debt. Similar measures were taken in other nations that defaulted and repudiated. In the end, they’ll probably prevent outlaw foreign transactions for a short while and do whatever to prevent currency from leaving the U.S.A.
Eventually, the dollar will most likely fall much with respect to several of the other currencies (see net energy commodities exporters and net manufactured products exporters).
Serious stuff, and time we engaged it with some concrete solutions.