If you have a lot of books (and you can take care of them very carefully) you can use your books as a way to back up your seed. Choose 12/24 books, depends on your seeds (or just choose 1, 2, whatever you wish). In each book, mark a word (or a font) that represent your seed with invisible ink. To make it easier to remember, use the 1st page of the first book, 2nd page of the second book and so on. Take care of your books.
This would work nicely, except under one important circumstance: if everybody uses this method, then everyone knows how to find everyone else's seed, look through their books with an ultraviolet torch
When you come up with a way of storing your wallet seed in a hidden way, take this advice: don't tell anyone (in particular, don't tell the internet

)