This article focuses on patent infringement issues associated with 3D printing, and conducts an analysis on the potential conflict between protection of patent rights and non-commercial private use in the context of 3D printing technology. Two characteristics of 3D printing are bringing challenges to patent law. First, 3D printing enables “digital manufacturing” and distribution of “virtual objects” via the Internet. Computer-Aided Design (CAD) files of existing patented products or key parts of existing patented products can be delivered instantly through the internet, and anyone having these files can “print out” the patented products or key parts with a 3D printer. This process thus increases the possibility for users to intentionally or negligently infringe existing patent rights. Second, 3D printing technology promotes “personal manufacturing”. Small 3D printers with reasonable prices are available for individuals, and there are many online platforms available to those who want to share designs of objects that can be manufactured with a 3D printer. Benefiting from these characteristics, end users are expected to perform a more decisive role in patent disputes than ever. Based on these characteristics, this article provides a comprehensive study of the Taiwan Patent Act, addressing the issues of 3D printing and patent infringement. Specifically, Part I explains the background of the issues. Part II explains the manufacturing process of 3D printing. Part III examines potential patent infringement liabilities in each step of the 3D printing process explained in the Part II, especially those related to digital manufacturing. Part IV discribes the rising of end-user infringement, and explores its impacts on patent law.