A kit for molding polymeric manufactured articles, of the type comprising a male mold part, provided with at least one first seat (3, 4) that corresponds to at least one first portion of the at least one manufactured article (6a, 6b) to be provided, and a female mold part, provided with at least one second seat (8, 9) that corresponds to at least one second portion, which is complementary to said at least one first portion of the at least one manufactured article (6a, 6b) to be provided, wherein: - at least one component chosen from said male mold part, said female mold part and at least one intermediate accessory plate comprises a protruding perimetric border (12, 13) which is delimited by substantially flat and regular surfaces, said protruding perimetric border (12, 13) comprising a through hole (16, 17) which leads to a groove (18, 19) of the inner face of said component, said groove (18, 19) connecting said through hole (16, 17) to the respective seat (3, 4, 3a, 4a) of said component; and - at least one additional component chosen from said female mold part, said male mold part and at least one intermediate accessory plate comprises a recessed perimetric indent (14, 15), delimited by substantially flat and regular surfaces, said perimetric indent (14, 15) having a shape and dimensions which are complementary to those of said protruding perimetric border (12, 13) for a respective hermetic coupling when said male mold part and said female mold part are mutually mated so as to define the cavity that corresponds to the manufactured article (6a, 6b) to be provided characterized in that said at least one additional component comprises a complementary groove with shape and dimensions complementary to those of said groove (18, 19), when said male mold part and said female mold part are mutually mated so as to define the cavity that corresponds to the manufactured article (6a, 6b) to be provided; said hole, said groove and said complementary groove defining the channel for the injection of the polymer into said cavity. - at least one component chosen from said male mold part, said female mold part and at least one intermediate accessory plate comprises a protruding perimetric border (12, 13) which is delimited by substantially flat and regular surfaces, said protruding perimetric border (12, 13) comprising a through hole (16, 17) which leads to a groove (18, 19) of the inner face of said component, said groove (18, 19) connecting said through hole (16, 17) to the respective seat (3, 4, 3a, 4a) of said component; and - at least one additional component chosen from said female mold part, said male mold part and at least one intermediate accessory plate comprises a recessed perimetric indent (14, 15), delimited by substantially flat and regular surfaces, said perimetric indent (14, 15) having a shape and dimensions which are complementary to those of said protruding perimetric border (12, 13) for a respective hermetic coupling when said male mold part and said female mold part are mutually mated so as to define the cavity that corresponds to the manufactured article (6a, 6b) to be provided characterized in that said at least one additional component comprises a complementary groove with shape and dimensions complementary to those of said groove (18, 19), when said male mold part and said female mold part are mutually mated so as to define the cavity that corresponds to the manufactured article (6a, 6b) to be provided; said hole, said groove and said complementary groove defining the channel for the injection of the polymer into said cavity.