A plastics gutter fitting (8, 11) has at least one transverse groove (10,17) receiving a sealing strip (16) and an inwardly turned clipping nib (9,15) extending across at least one end of a said transverse groove (10,17). The fitting is molded using a three part core of which two outer parts (4,4') can be moved convergently relative to a central part (3) for releasing a molding (8) therefrom. This molding method enables the reentrant where a clipping nib (9,15) extends across an end of a transverse groove (10,17) to be molded integrally in the fitting.