Hello,
from various information sources, by summary concludes the current seed phrase storage as best:
2 of 3 multisig.
My understanding is a seed phrase will have 24 words.
These 24 words are then engraved onto 3 stainless steel hexkeys, so when 2 of these hex keys are brought together, the 24 words are revealed.
Then the user needs to enter the passphrase to fully recover the wallet.
So, is there a cold wallet with the software to make the multisig, as I don't know how to 'split' the 24 words into the 3 engraved stainless steel hexkeys?
Op if you are talking about an offline backup most times referred to as paper wallet backup, you can split the seed phrase into 3 places or two places depending on your preference anyways you have to make sure that in the course of doing this the seed words are still arranged serially like in your wallet creation device. For bitcoin the seed words is defaultly 12 words though you can extend them with custom words or even increase the word count to about 18 or 24.
Anyways I personally don't fancy splitting the seed words because of the idea of misplacing one of the combinations or worse mixing them up. As for hex it's more of a private key thing and no one would want to go through the stress of engraving a master key on steel. Besides that all keys are generated from the seed either directly or indirectly.