There are several ways to secure passwords with an automated encryption algorithm, but sometimes it's best to write it down on paper and keep the paper itself secured. Hackers can't easily get to paper. However, if someone finds that paper, they can see the passwords plainly.
What's a non-automated method of securing information on a piece of paper? For example, have the real password be in every other character (eg p1a2s3s4w5o6r7d8 = password).
Have a look here for some history and ideas about steganography ;) Your example is a simple working one, you can even use an invisible ink or write it backwards with only every 5th character relevant etc., it is up to your imagination :)
Take a character sequence from a book you have lying besides your computer. You can take the sequence in any number of ways: First/second/etc. letter of each word in a chapter you decide, for example.
What youre suggesting is a simple cypher. I'm not sure why you'd want to implement something like that vs. using a password manager like KeyPass but you can us a simple substitution cyper where A=Z, Z=A etc. if you need to write it down.