You don't have to manually write it on paper. Printing it, maybe even including QR-Codes also does the job. Just don't leave it accessible for everyone in the house. I had someone break into my home once. They just took Money. They didn't steal any laptop or external HDD, nor any USB-Stick. But because USB-Sticks can easily get lost or stolen I'm not a friend of storing important data on it, at least not as the only place. I think it is better to store important data only in an encrypted container in several places, maybe even also in the cloud for you to be able to access it even if your house and all your technical equipment burns down.