The pilot advised that shortly after the aircraft entered the first of what was to be a series of aerbatic manouvers, the aircraft's left rudder cable failed. After establishing what degree of flight control was still available, the pilot was able to make an uneventful landing. Later examination found that the rudder cable had pulled through the rear swage fitting at the rudder horn end. The investigation found that both the left and right rudder cables were replaced at the last periodic maintenance inspection only three flight hours prior to the incident. An examination of the manufacturers cable making processes revealed that the clamping tool used in the manufacture of the failed cable was not adjusted correctly. It was also found that there were significant wall thickness variations for the type of swage sleeves being used. All cables previously manufactured by the particular method used for the failed cable were identified and withdrawn from service. The manufactures cable making process for the failure type are currently under review by the CASA.