cut a stout twig that has another smaller branck sticking from its side,now set the the base of the stick on a smooth rock,and now make sure the top of the stick is on the very edge of the  rock,when the game goes for the bait it hits the side branch and knocks it from both the edge of the rock and the smooth stone which it sits on. a sure fire and rather sensitive trap,almost as sensitive as a fig four but far less complicated