This teaching manual introduces to the concept: reverse engineering of physical objects. It provides technical aspects of reverse engineering, such as definitions, introductions of different types of 3D scanners and their applications. It also provides the practice of reverse engineering ranging from the complete progression of data acquisition procedure to the post-treatment processing step. Reverse engineering is the process that identifies an object, a device, or a system technological property by performing a comprehensive analysis of its structure, functions, and operations. In mechanical engineering, this process aims to create a virtual 3D model from an existing physical object to duplicate or to enhance it. They are many reasons to use reverse engineering of physical objects. For example, the reverse engineering process will be used if the original design is not supported by sufficient or adequate documentation or if the original CAD model is not appropriate to support modifications and/or standard production methods. In some cases, original manufacturer no longer exists nor manufactures a product, but some requirements remain for that product. Reverse engineering would then help. In the case of worn or damaged components, for which no source of supply is available, reverse engineering building features would also to analyze competitors' products features, for performance improvement and/or product features, for lack of additional parts (spare parts) or to update obsolete materials or antiquated manufacturing process. On the other hand, 3D printing or additive manufacturing is the construction of a three-dimensional object from a CAD model or a digital 3D model. The term "3D printing" can refer to a variety of processes in which material is deposited, joined or solidified under computer control to create a three-dimensional object, with material being added together such as liquid molecules or powder grains being fused together, typically layer by layer.