1. Plastic bottle - 1
2. Balloons - 3
3. Y shaped tube - 1
4. Cork
Methodology of making:
1. Make a incision in the middle of the bottle.
2. Use some tools to make a hole in the cork and fix the one end of the Y shaped tube.
3. In the other end, fix the two balloons and put it inside the bottle.
4. At the bottom the bottle, cover with the 3rd balloon's half portion.
Making of lung model
Working methodology:
1. Hold the large, bottom balloon and pull it downwards slowly.
2. Observe the changes in the two balloons attached with the Y tube.
3. When, pulls down, both balloons inflate and deflate, due to pressure inside the bottle as like in your lungs.
Exhalation and inhalation
Now we'll wrap up our bottle lung model by comparing it to our respiratory system and discussing the model's shortcomings.
Thoracic cavity  
Bottle lung
This cavity filled with pleural fluidBottle filled with air
Trachea is flexibleY-shaped tube is rigid
Diaphragm flattensBalloon drawn downwards
Lungs made of alveoliBalloons empty
Ribs moves and changes the thoracic cavity volumeBottle does not move