When I was a child, I naively believed that with an endless supply of gears and screws, I could create everything in the world. This fascination with machinery is not unique to me, many children are drawn to the operation process of various mechanical devices, some even try to make them by themselves. However, making mechanical devices is not an easy task. In our app, we use a simple method to guide children to make some simple and interesting devices, helping them understand the operating prin