I am a 8th grader and I built this onager for my science fair project. All the metal was laser cut at my dad's work. It took about two weeks to build, just because of all the trips we made. This compact machine launches a golf ball over 175 yards. I am working on a better trigger system now and looking for a crank so we can go over 40 pounds of force. I am hoping to get a video up soon.