This paper presents the construction of 3D rapid prototyping (RP) physical models for computer tomography (CT) medical images. By using STL (Stereo Lithography) triangular meshes as basis for 3D construction, the process for RP model construction can be simplified via point data without turning them into curves. Grey prediction theory is used to sort out contour point data in each layer of the medical image. Using contour difference detection operation, the sequence is completed operation through the cross-sectional contours. The 3D solid model constructed via layer by layer meshes is to build the STL file. After saving as STL file, 3D solid model of the medical image is displayed with RP and its virtual reality presentation. Two case studies, human braincase and femur bone are used as case study for construction of 3D solid model with medical images. The method is successful and a number of steps are simplified. The two solid models are compared with curves swept-blend CAD models for analysis. The results show that differences between the two methods are in an acceptable range; therefore, it is shown that this method is feasible for reconstructing 3D models from CT medical images.