We have developed the direct inkjet 3D fabrication system which can vary mechanical strength of nano-composite hydrogels on demand. The object body contains various parts which have gradual strength, colors and other physical properties. In addition, over-hanging and hollow structures were successfully obtained by using support material. It can be said that the hydrogel 3D fabrication system is able to construct a fine objects having partially controlled mechanical strength. Those objects have a potential of adding a unique value into the medical 3D model, and other applications. The methodology of hydrogel fabrication and the properties of the hydrogel object are discussed, and the blood vessel model and the hollow vascular model were prepared for surgical training application.