PLA (Polylactic acid) is thermoplastic aliphatic polyester made of renewable resources like corn or starch that is an environment-friendly material. It has higher rigidity, strength and stiffness compared with ABS, and does not need to close the cavity, no warping, no cracking, low shrinkage rate, limited smell when printing, safe and environmental protection. It is easy to print and has smooth surface, can be used for conceptual model, rapid prototyping, and metal parts casting, and large size model.