1.pangolins.stl is the first edition file
2.pangolins-1.stl is the second edition , fixed the back part , and the movable part is much loose
3.pangolins-2-tight.stl is the third edition , fixed the pangolins-1.stl is the much tight
三個版本的可動關節穿山甲，pangolins-1.stl 是修正背板較鬆版本，pangolins-2-tight.stl 是關節較緊版本
