This decision maker works on a simple scientific principle and can easily fool your friends! Why not make one and fool them by controlling the answers that the decision maker gives to their questions? The decision maker looks like an octopus trapped in a bottle, but it's really just an eye dropper with a face painted on and some decoration added. If you don't have an eye dropper handy, you can buy one from most chemist shops. You need to fill the eye dropper with a little water - just enough so that when it's placed in a bowl of water, it will rest just below the water. Next, take an empty two litre pop bottle. Rinse it out, peel off the label and then fill it full of water. Put the eye dropper into the bottle. If any water spills over the top, don't worry - just wipe it up. Screw on the cap of the bottle. That's the basic make completed! When you squeeze the bottle, the eye dropper will sink to the bottom of the bottle. And when you let go, it'll rise up to the top. Why? Well, squeezing squashes the air in the eye dropper, letting more water into it, so it sinks! And when you let go, the reverse happens. As well as adding some decoration to the eye dropper, we also jazzed up the background by sticking some card to the back of the bottle and writing onto it various answers ranging from yes to no. Put no at the bottom and yes at the top. Practice with it, then get your friends to ask the decision maker some questions. Squeeze and release depending on the answer you fancy!