Saw that yesterday and seemed pretty cool to cut out the subway and just fold up the flaps. Wonder if this is standard whitewood practice these days or something they thought up. As long as the metal was thick enough not to deform over time I don't see why it would just be the prototype method honestly... Seems fine for production as well.. With the added benefit that you might be able to keep the subway cleaner by being able to blow it out with some air duster without dismantling?