Now it is a real snap to assemble your catapult arm to the base. Simply push the metal bar through one upright, feed it through the catapult arm then push the bar right into the other catapult upright. This picture shows it complete. Put a dab of glue on the bar at each upright so it will hold tightly and if your catapult arm is a bit loose you may want to put a few wraps of tape on each side of the bar near the arm so it is held in the center of the bar.