Before I used a password manager, I used three random word phrases, but with the first word lowercase, the second upper case, and the third (chosen to contain at least one of "aeio") with tr/aeio/4310/. This gave phrases that passed requirements like "must contain a mixture of upper and lower case" and "must contain at least one number". It also increased the search space for guessing. In some cases I had to chuck a "!" on the end to meet a "must contain a symbol" requirement.

"crystal lizard rekindle" became "crystal LIZARD r3k1ndl3" etc.