Here's a neat project for Dyson and other companies. Try to figure out a way to create a double-fan. A double-fan is a fan with parallel blades located almost next to each other inside the same metallic-ribbed case. Now, constructing the design for this fan might seem simple; however, it's much more difficult than slapping together aesthetic appearances. The problem with this type of fan is that since both blades are parallel to each other, the air passing through each blade is transferred through the opposite blade. Therefore, while one person is enjoying the cool breeze of the fan, the other person is stung by the warmer air, which has passed through to his or her particular side of the fan. Now, the trick is to get the parallel blades to both produce cool air for both recipients instead of only one. Furthermore, they must figure out a method for canceling out or greatly reducing the negative warmer air from passing through each blade to the opposite blade like an invisible game of ping-pong.