Catapults vary in design but have a number of features in common, a rigid frame is held in one hand and rubber bands power the ammunition toward its target. The materials of the frame vary widely from a natural forked branch from a tree to the latest space age high tech polymers and laminates. The bands on the other hand are almost always latex rubber in varying thicknesses and shapes.
A catapult frame must be comfortable to grip and easy to aim and the bands should be powerful enough to to the intended job, if that is hunting that means they must be able to dispatch the quarry quickly causing the minimal amount of suffering. However if they are being used for plinking enough power to knock over a tin can may be plenty.