A plastic injection apparatus for making shoes that includes one molding block composed of two halves that define a cooperative cavity for forming the sole of the shoe and two shoe molds of different contiguous sizes. The cavity includes an inwardly extending peripheral flange at its upper edge. The shoe molds have such dimensions that an adjusting peripheral line is defined around each one of the shoe molds of such dimensions that when both shoes are placed in the molding block, the flange is brought adjacent to the adjusting peripheral line.