Why not just print out the possible words, number them and select 24 of them by coin-flipping or using dice?
I lost you there... could you please elaborate? How would i integrate checksum?
good point. I was a bit naive and thought any combination of words would be a valid passphrase. I'm not sure this is the case.
Although using a mnemonic not generated by the algorithm described in "Generating the mnemonic" section is possible, this is not advised and software must compute a checksum for the mnemonic sentence using a wordlist and issue a warning if it is invalid.
Not sure how trezor handles this.
There is no checksum in seed, any combination of words (of bip39 list) is just fine as long as they are truly random and not chosen by a human brain.