The arms each have a vertical plastic tab attached just below the elbow joint. (Figure 6) A metal pin that is connected at a slight angle to the side of the body frame goes through a hole at the top of the tab. As the monster's body moves from side to side, the tab slides up and down on the pin. This makes the forearm move up and down.
The inside bottom of the front and back body panels have molded plastic gear teeth (Figure 7) that fit into similar gears at the top of each leg. (Figure 8) Each leg has a metal pin through the leg where it enters the boot. This allows the legs to move from side to side. As the body moves from side to side, the gears cause the legs to move in the opposite direction.