Bip39 Rust Crate 1 example of manually making entropy will be flipping a coin. But if an attacker provides a coin that may be weighted slightly in favor of heads, your Original source of entropy will likely have been corrupted. Listed here are 5 solutions to create a seed phrase, https://social4geek.com/story4099209/generator-seed-phrase-the-fact-about-bip39-that-no-one-is-suggesting