I am wondering where I can stamp something into metal on my own.
Asking a third party to do that for me, doesn't seem like a good idea.
It can be trustless. Check out how woodwallet does it. I think they use bip038
I have a fairly strong opinion that if you have an encrypted wallet, there is zero need for any additional layer of encryption.
Similarly, if you have a single private key, you encrypt it once, but to do this you can't trust other peoples' algorithms and "help."