Re: I made my own Water/Fire-proof Metal Bitcoin Cold Storage, short guide.
This is better than a paper wallet, but I don't think this material will survive from rust and it will ruined, rust will destroy the "relief" including all your wallet code.
Also, how about storing it in a zip lock bag with some desiccant (the sachet from my next pair of new shoes). Or rice. By preventing the moisture in the air getting to it degrading of the metal would be a lot slower. It is stainless steel so it will be very very slow, and on my first test I left the back exposed when etching and it just "pitted" rather than an all over rust.
There's really no need to. He said it's stainless steel, so it's basically what the inside of a water boiler or your dishwasher is made of. It can withstand being submerged in boiling water for months and not have a speck of rust
It's also quite resistant to weak acids, salt and other chems. You only have to make sure the etches are deep enough so that normal scratches and metal wear won't make it unreadable.