heard a guy on WBD talk about flipping a coin 256 times, creating a binary, then converting it Hexadecimal and then converting it to a private key that could be imported into Blue wallet, wanted to mess around
Discussion
You can definately do this, the only missing part is the checksum calculation. Some options:
https://github.com/massmux/HowtoCalculateBip39Mnemonic
https://github.com/bitaps-com/mnemonic-offline-tool
and above mentioned coleman.
And of course, a SeedSigner can also do this. It will adjust the final word to a valid checksum (IIRC).
Please use these safely, e.g. offline when doing this for reals.