If I had a billion dollars and I had any reason to fear that the government might someday for some reason seize it, I would create the financial equivalent of a “life pod”: I would establish an irrevocable trust whose purpose would be to take care of me for the rest of life if I ever became bankrupt. I would live in a house owned by the trust, drive a car owned by the trust, eat meals prepared for me, use a credit card paid by the trust, etc.
Mattress length/width dimensions are standard in the US, but height varies a bit. If we assume a little under a foot thick (high, but not unreasonable for the ones that have built-in “toppers” on them), a king size mattress has a volume of about 40 cubic feet.
Let’s assume you like a very, very firm mattress (i.e., we can use the entire interior volume for bills). At least it will be more comfortable than Susasannan’s mattress filled with depreciating gold.
Using numbers found on the Internet (which would never lie to me), a (US) billion dollars in hundred dollar bills takes up just less than 4800 cubic feet. So you’ll need about 120 mattresses to store your bills (plus a single pea to place under the bottom one).
Unfortunately, this means our days are numbered, as we have now discovered the secret reason for those mattress stores that can somehow manage to be on every corner, despite most people only buying a mattress or two per decade. The mattress mafia will be after us, since clearly these stores are fronts for currency shipments.
I’m reminded of one of the few actually amusing scenes from the godswaful Macauley Culkin Richie Rich movie. Van Dough had finally gotten into the Rich family vault, and finds that it’s full of keepsakes whose only value is sentimental. He starts ranting and demanding to know where the money is; Mr. Rich looks at him like he’s trying to figure out how someone this stupid manages to feed and dress himself and tells him the money is where anybody with a multidigit IQ would expect: in bank accounts and the stock market and real estate and various other investments.
Your campaign had one of those DMs, too? 
About 200,000-300,000 new bills can be stuffed into a 6’ by 6’ king size mattress depending on the thickness of the mattress. Less if the bills are unmarked.
What do you think this would accomplish?
It would stop the government from outlawing trusts and seizing any money in any trusts.
Oh wait…
So a mid-sized motel should do the job.
Yeah, if I had oodles of money and wanted a “life pod”, I’d be more literal about it: Construct a self-sufficient, off-grid home, with plenty of space for gardens around it to grow food, and next to a reliable river or stream. Which the government could still seize, if they put their mind to it, but they at least couldn’t do so at the stroke of a pen.
This is a link to the Snopes article about drug raid that Mexican authorities did back 2007 where they found a room that had $205.6 million in U.S. currency in it. There are pictures of the cash in the article.
The main downsides, of course, of storing that much cash is it can be stolen if not secured properly or it could go up in smoke if the building it is in catches fire.
They should have kept printing $10,000 bills, given how inflation has eaten into the value of a mere c-note.
It would stop a RICO/ civil forfeiture type seizure of assets because the whole point of an irrevocable trust is that legally it isn’t your money anymore. Of course a sufficiently despotic government can chuck the law in the trash and just impound wealth but that’s not going to happen as long as the movers and shakers expect protection of their assets.