4M Motorised Barirer Gate

Build this motoried robotic barrier gate to stop  intruders into your room. It’s a cool mechanical science gadget.
HOW IT WORKSThe motor has a worm gear that turns a shaft that raises or lowers arms A and B. The metal on the card completes a circuit that allows the motor to run when you press the UPPER button. The joint mechanism raises the outer end of the barrier when the inner end lowers, and lowers the outer end of the barrier when the inner end rises.
Requires two 1.5V AAA batteries (not included)
For age: 5 years and above.