The one in question: Hello, I currently have to build a timer for my high school physics class. I plan on using a very similar design structure as shown in the video. However, I would like to know if there is a mechanism/modification I can do to this so that I can stop/greatly reduce the flow of water by pulling/twisting/switching something. My goal is to make this device acts more like a stopwatch than a timer. Currently, I'm thinking the best way to do it is to somehow block the flow of air from one of the tubes so that the water slows down to a drip. I'm having a hard time figuring out how to do it though. Any help/advice would be greatly appreciated. And sorry if this is the wrong category to post in, I'm new to this forum and this category seemed to fit best. Thanks again!