This is one of the easiest basic mechanical traps to learn and construct, provided you have a cutting edge such as a rock or knife. It uses a weight as a dead-fall to pin or kill your quarry.
Figur-4s can also be constructed without a cutting edge. Knots or natrual bends in the sticks used can create the mechanism necessary for the trap to work.
NOTE: In a serious survival situation setting traps for anything smaller than a chipmunk may not be worth the caloric effort of setting up the trap.
WARNING: Most primitive traps are illegal to use in most states. Unless under a life-or-death survival situation it is not recommended that you use them.