The present invention relates to a new and improved stereolithography method and system for generating a three-dimensional object by forming successive, adjacent, cross-sectional laminae of that object, thereby providing an object being specially processed to reduce differential shrinkage. A welding device comprises first and second electrodes or conductive ends that extend along substantially the entire extent of first sides of the first and second weldable members, respectively. The two hand levers form a pliers In the casing a bore is disposed for guiding a rack consisting of steel, one end of which cooperates within the bore with the pinion sector such that an expansion wedge can be displaced outwardly by a closing movement of the two hand levers. The first polymeric material is introduced in a molten state into contact with the reinforcing composite layer. A second operating element is provided, upon the actuation of which the first fitting and the free-pivoting device are unlocked, The driver of the first fitting receives the transmission element \u2014coupled thereto for carrying along, wherein free travel in one direction of rotation is provided between the driver and the transmission element.