Filamentous materials (mainly engineering plastics here) are melted, then extruded through a nozzle and piled up layer by layer. This process uses nozzles instead of lasers and carving knives. (At present, the mature 3D printers on the market are basically based on this molding technology, and the molding materials are PLA, ABS, PC, nylon, artificial rubber, paraffin and so on. ; At present, the main materials on the market are PLA and ABS. Its main features are: small size, easy maintenance, easy operation, safety and low cost.