The basket is first moulded such that at the extremities of the lower parts 16 of the side walls 12 are provided supplementary volumes 36 into which the injection points 24 of the plastic material open. After moulding, the supplementary volume 36 are removed by cutting along a plane P in order to obtain the final article of the required size. The invention eliminates from the final article the injection traces and zones which contain internal tensions which can in turn cause cracks.