Generate original seed word list by combining 2 out of 3 (x out of y) seed word lists.
Ran across [this comment by u/Frogolocalypse on r/bitcoin](https://www.reddit.com/r/Bitcoin/comments/75kw5t/practical_way_to_split_a_bip39_seed_into_a_2_out/do757y6/) and thought it was pretty neat.
[Shamir's secret sharing](https://en.wikipedia.org/wiki/Shamir%27s_Secret_Sharing) is a way to take a message (like a seed list) and produce a number of encrypted fragments, where you need x number of those fragments in order reproduce the original. 2 out of 3, 3 out of 5, it's a good way to make any one physical recovery scheme useless without the rest, but also allow for any one or some to be lost and still be able to recover. You can use your imagination on how one might use this.
**EDIT:** Original work - mash of BIP39 with Shamir's Secret by u/iancoleman found here: https://www.reddit.com/r/Bitcoin/comments/6y5pu5/shamir39_mashup_of_bip39_mnemonics_and_shamirs/