"Well, there must be SOME sort of machinery now that can do it. " Pretty vague here, but I recall hearing / reading that one method is to put the nuts in a big pressure-drum, then suddenly release the pressure, and the nuts popped themselves open..... perhaps some critical timing or pressure to be sure the shells just popped and not the whole nut meat exploding with the "bends" . Sure to be the expensive machine to get started, and needs a ready market for the nuts to pay for it all. so far not here in N.Z. sigh.