Here are some images of Corel Models 1/25 scale Onager Catapult. The Roman Onager was a field and siege catapult and is believed to have been invented sometime in the 3rd and 4th centuries A.D. It is believed the Romans got the idea for this catapult when they had seen a wild Donkey being chased by hunters kicking back at them the stones it had come across on the road. Hence the name Onager which is a type of Donkey. The materials for this model were Walnut, Brass and copper and was a straight forward build.