This guide illustrates the 3D Printing for Repair (3DP4R) process. It provides repairers with guidelines and tools to produce 3D printable versions of the spare parts required to repair a product. In the guide, we provide guidance specific to Fused Deposition Modelling (FDM), since it is the most available and common technology for 3D printing. The information provided for the Analysis phase, Test phase, and much of the Redesign phase can be used with other technologies as well. This guide was developed as part of the Sharepair [1] project, which offers a variety of tools and information to help and support the repair of products by do-it-yourself (DIY) and volunteer repairers. This guide is meant for anybody who is interested in trying to manufacture spare parts with 3D printing technologies, remakers, tinkerers, volunteer repairers, professional repairers, and everyone who is interested in repair initiatives. The 3DP4R process consists of four phases: Analysis, Redesign, Manufacture, and Test, as shown in Figure 1.