That looks *neat*. Is it at all waterproof? Or does dropping a bit of water on it cause the ink to run? Maybe "alumajet" plus something like Krylon Preserve It spray would be an interesting combo. Speaking most generally though, isn't aluminum a pretty "reactive" metal? Not sure it's a good choice for long-term storage... But agree this would be gorgeous e.g. for gifting bitcoins short-term!
I like the idea behind the product, and might even try printing some photos (color management nightmare, probably), but would not trust it for btc wallet any more than paper.
actually it has some sort of special covering on one side which is the printable one (has to be single face, but it folds nicely) because the ink doesn't stick well on the other side.
and it can tolerate some water when printed with a regular canon printer