This is a fully functional Trebuchet catapult model that measures a whopping 220x140x130mm. The Trebuchet is one of the most powerful and accurate catapults and it was king of the siege-engines during the Middle Ages. This is a simplified model suitable for 3d printing and it still operates under the same principles as the true originals, and can fling payloads a good distance. Read the instructions for some important building notes. Please post some of your action pictures if you print one! Enjoy!The model comes with three types of interchangeable counterweights: 2 cosmetic stone-carriages and 1 basket version if you want to operate it with force. Fill the basket with a heavy load such as spare metal screws, washers or whatever you have available, or even pure lead-blocks for optimal performance. Included are also two optional arm stabilizing washers. Depending on the build quality and measurements you might need these, or you might not. If you run into a problem where the arm rocks too much from side to side and causes the counterweights to hit the structure during launch then slide these on. Of course, I wouldn't be fair if I didn't also throw in something to launch! Therefore you will also find two different ball-type payloads to use with the catapult. The main structure can be built without rafts or support. The basket counterweight can also benefit from this. The arm, the two cosmetic counterweights and ball payloads could use some printing support. Good luck and have fun!