First you tie your victim up and put a mega phone in front of there mouth so the screams are magnified then get small razors that will not cut into veins and such and kill them but will cut deep into skin and put them on a giant, body shaped grid above the victim. Inside the grid there are chains and pullies that work on the screams of the victims, so as long as they scream, it runs and you put a pendulum with the small razor on it in the grid so it swings from side to side and you put it above the victims feet then you stab the victim in the hand to start the screaming and the pendulem swings