For those who followed the ways previously mentioned now you have to be able to create and verify the correctness of BIP-39 seeds yourself (with nominal aid from tools like binary to hex to decimal converters). This text points out BIP39, the standard that defines how seed phrases are made, https://travialist.com/story9245730/helping-the-others-realize-the-advantages-of-bip39-seed-phrase-mnemonics-generator