I have studied an Eister box rather closely ..I would agree with Jimmy , its tapered ,bent and filed . That's not to say he always did it this way ,but the one I inspected was ..Another thing I thought interesting , the end of the lid fold was not a straight cut ,it was filed in a saw tooth pattern ..These were something under an 1/8 inch tall . Don't recall exactly ...I can think of no other reason for these but decoration .....Louie