The balloon diver is easy to make. You will need a balloon, a plastic shampoo pouch, paper clips and a bottle full of water. Attach a paper clip to a balloon and place them in a bottle full of water. Because of the paper clip weight the balloon must just float in the bottle. Close the lid tight and press the bottle from the outside. A little bit of water will enter the balloon which will make it heavy and it will sink. On realizing the pressure the balloon floats to the top. Enjoy the up-down movement of the balloon in a close-up. On pressing the bottle the balloon sinks, on releasing the pressure it floats up. You can also adjust the pressure from the outside so that the balloon floats midway.
Now take an empty shampoo pouch and cut a “V” notch in it. Attach two paper clips so that it just floats in water. Fold the pouch and insert it in the bottle of water. Screw on the lid. Press bottle from outside and the pouch will sink to the bottom. On releasing pressure it will float up. This is a low-cost fun game.