Very important warning: when punching the 4 letters of each word on each of the washers, make sure you also punch the seed index of each word/washer (i.e., its order position in the seed). If you don't, and you just rely on the washers being arranged in proper order in the screw, you may mess things up if you or someone else unscrews it and the washers fall off. If the order is lost, the seed is also effectively lost.
If the seed phrase is 12 words, that's 12 washers. The number of permutations is n!, which is 479,001,600.
This guy cracked 1 trillion seeds in 30 hours using cloud computing. So it should take less than one minute to recover the seed.
edit: only first four letters of each word are needed to unambiguously identify seed words, so it's !12 not !16 as I first thought.Ah yes. That is why 12 word seed phrases are not, imho, the right choice for one's deep freeze wallet.