Regarding this stainless steel capsule, I think the capsules sailors use to store medicine, for example, could work, as some are made of stainless steel and, above all, waterproof. They don't cost much. However, in the event of a fire, I suspect the paper inside will burn, unless the capsule is buried deep in a garden. Unless, perhaps, you place several capsules inside each other like Russian dolls (matryoshka).
But what would be interesting to check first and foremost is how you created your wallet in the first place. Imagine if your wallet was emptied after several years because you created it online on a dubious website?
https://talkimg.com/images/2025/05/28/UXnG5H.jpeg
because the fire will burn everything but with solid and strong material protection it may still survive.
this is only optional and there are some other products that can be used and are stronger and maybe as you mentioned in the image.
And of course creating an initial wallet that uses the Website online will have more risks because some are not trusted.
But creating your own from a trusted wallet like Electrum and then recording it elsewhere might be safer.
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3 - Hardware wallets: HWs (mainly open source and air-gapped) combine the best of both worlds: the security of a paper wallet and the convenience and ease of a software wallet.
I intend to open a topic soon to address these questions in more detail.
I use safepal and it is still comfortable until now, Without any connection and only using Air-gapped which operates completely offline. 3 - Hardware wallets: HWs (mainly open source and air-gapped) combine the best of both worlds: the security of a paper wallet and the convenience and ease of a software wallet.
I intend to open a topic soon to address these questions in more detail.
These wallets isolate devices that store private keys from any external network, including the internet.