Providing the natural mapping between multi-touch gestures and digital content manipulations is an important factor of friendly user interfaces. Although, in the literature, there are some guidelines available for 2D digital content, the guideline for the manipulation of 3D contents is yet to be developed. In this research, two sets of gestures were developed for experiments. For comparative studies of age differences, 30 participants, including adults and children, were invited to carry out three tasks relevant to rotating the digital model of a green turtle to explore its features. The results showed that simpler gestures could facilitate the mapping between 2D control movements and 3D content displays, especially for children without intrinsic mental models of virtual contents manipulation. Although participants tended to visually observe the feedback angle of the contour and use the head of green turtle as a manipulation reference, it may not be easy to identify and manipulate the 3D object without a clear convex shape or image. In addition, offering a robust mechanism for gesture inputs is necessary for universal control of such a system. While manipulation, providing a synchronized mapping instruction for three axes rotation on screens is a useful 3D objects rotation solution for touch-screen design.