Stereolithography apparatus comprising a container for resin intended to be solidified by a polymerization process which container comprises two opposite walls (101;2) movable in a direction approaching them and moving them away from each other, substantially in a manner parallel to each other or along a path whose axis is transverse to the surface of at least one of the said two walls; a first wall being transparent to the direction of propagation of an electromagnetic radiation by means of which said resin is radiated; a second wall being composed of a movable adhesion platform placed in contact with the resin, a motorized mechanism progressively moving the movable platform away from the first wall with a stepless motion or by advancement steps; an electromagnetic radiation source that generates an electromagnetic radiation beam with a predetermined distribution of the intensity of the radiation variable in a plane parallel to said first wall; a modulator for the intensity of the electromagnetic radiation that changes the distribution of the intensity thereof along the plane parallel to said first wall in a manner synchronized with the advancement of the movable platform and in a manner corresponding to the cross-section shape of an object to be produced, along a section plane of the object which section plane is parallel to said first wall and intersects the object to be produced in a position along the axis thereof parallel to the direction moving the movable platform away from said first wall which position corresponds to the distance between said first wall and said movable platform and wherein said first wall and said second wall acting as the movable platform are connected with each other along the whole perimetral edge by a shell wall made as extensible in the direction moving said two walls with respect to each other, while said first wall, said second movable wall and said shell wall form a chamber progressively adaptable to the shape of the object to be produced and sealed towards the external environment and a vat being provided which is delimited by the first wall and a shell wall and wherein the vat and the second movable wall are made as cartridges or elements detachable from and attachable to the apparatus. a container for resin intended to be solidified by a polymerization process which container comprises two opposite walls (101;2) movable in a direction approaching them and moving them away from each other, substantially in a manner parallel to each other or along a path whose axis is transverse to the surface of at least one of the said two walls; a first wall being transparent to the direction of propagation of an electromagnetic radiation by means of which said resin is radiated; a second wall being composed of a movable adhesion platform placed in contact with the resin, a motorized mechanism progressively moving the movable platform away from the first wall with a stepless motion or by advancement steps; an electromagnetic radiation source that generates an electromagnetic radiation beam with a predetermined distribution of the intensity of the radiation variable in a plane parallel to said first wall; a modulator for the intensity of the electromagnetic radiation that changes the distribution of the intensity thereof along the plane parallel to said first wall in a manner synchronized with the advancement of the movable platform and in a manner corresponding to the cross-section shape of an object to be produced, along a section plane of the object which section plane is parallel to said first wall and intersects the object to be produced in a position along the axis thereof parallel to the direction moving the movable platform away from said first wall which position corresponds to the distance between said first wall and said movable platform and wherein said first wall and said second wall acting as the movable platform are connected with each other along the whole perimetral edge by a shell wall made as extensible in the direction moving said two walls with respect to each other, while said first wall, said second movable wall and said shell wall form a chamber progressively adaptable to the shape of the object to be produced and sealed towards the external environment and a vat being provided which is delimited by the first wall and a shell wall and wherein the vat and the second movable wall are made as cartridges or elements detachable from and attachable to the apparatus.