Methods for combining a tubular net with a carrier casing are disclosed. Air is blown into a carrier casing so that it is inflated to have a circular diameter. The inflated carrier casing is pulled in the direction of a tubular net toward a pleating head. The tubular net has holes and an open end of the tubular net is attached to a clamp. The inflated carrier casing is fed into the tubular net while pulling the net inside out over itself. The inflated carrier casing covered by the tubular net is pulled through the pleating head (which constricts the carrier casing) toward a shirring machine that includes the shirring mandrel. Air is blown from inside the shirring mandrel at a pressure that forces at least some areas of the carrier casing between the holes of the net to form protruding bulges, and the net/carrier casing combination is shined.