A method of manufacturing an object by stereolithographic 3D printing, wherein the object is built on a building platform layer-by-layer to obtain a stack of structured layers, wherein each structured layer is obtained by curing a photosensitive resin according to a desired pattern, wherein a film of removable material being different from the photosensitive resin is arranged between two adjoining layers, wherein in a post-processing step said film of removable material is subjected to a physical and/or chemical process that causes the first film of removable material to disintegrate or lose its stability and the removable material is removed from the object.