Video: How many times have you accidentally given yourself a papercut after excitedly tearing open a delivery? As Japan’s most resourceful knife maker demonstrates, those papercuts could be a lot worse if you spend hours painstakingly turning those cardboard boxes into a razor-sharp chef’s knife.
The process involves soaking the cardboard in water, repeatedly folding it over on itself, squeezing out all the moisture, pounding it flat, and trying to get the cardboard to dry as thin, dense and stiff as possible.
There doesn't appear to be any liquid plastic resin added as a stiffener, but at one point the excess cardboard is shredded, soaked and boiled, presumably to extract all the glues holding it together, which the cardboard blade was soaked in to improve rigidity.
So while the results successfully slice and dice, this is the last utensil in your kitchen you'd want to toss in the dishwasher.