&lt;p&gt;The 3D Printing In Zero-G (3D Print) technology demonstration project is a proof-of-concept test designed to assess the properties of melt deposition modeling additive manufacturing in the microgravity environment experienced on the International Space Station (ISS). The lessons learned from this technology demonstration will be used for the next generation of melt deposition modeling in the permanent NanoRacks Additive Manufacturing Facility (AMF) as well as for any future additive manufacturing technology NASA plans to use, such as metals or electronics in-space manufacturing, on both the ISS and Deep Space Missions. This demonstration is the first step towards realizing a &amp;ldquo;machine shop&amp;rdquo; in space, a critical enabling component of any Deep Space Mission.&lt;/p&gt;&lt;p&gt;The 3D Print payload consists of a 3D printer (a two-axis extruder mobility system, a single-axis print tray mobility system, the extruder and accompanying feedstock cartridge, the print tray, Environmental Control Unit (ECU, a prototype for the permanent AMF), an electronics box, and all of the necessary cables and bolts to attach the device to the ISS Microgravity Science Glovebox&amp;nbsp;(MSG) cold plate, MSG laptop computer, and MSG power supply) and all identified spare parts. The 3D Print payload will operate within the MSG. The payload uses extrusion-based additive manufacturing technology to fabricate objects. Additive manufacturing is the process of creating three dimensional objects from a Computer Aided Design (CAD) model where material is deposited layer by layer. The 3D Print payload will extrude a bead of thermo-polymer material from a larger diameter feedstock material. When one layer is complete, the next layer is printed on top and bonded to the lower layer while still molten. This creates an adhesive bond as opposed to a solid material extrusion.&lt;/p&gt;&lt;p&gt;Performance goals were defined realizing the 3D Print is a technology demonstration. The following is a list of minimum success criteria:&lt;br /&gt;1. Successful integration and safe operation in the MSG on the ISS&lt;br /&gt;2. Demonstration of extrusion based additive manufacturing using polymeric material&lt;br /&gt;3. Successful extrusion and traversing&lt;br /&gt;4. Printing of one part while in ISS microgravity&lt;br /&gt;5. Mitigation of functional risks for future facilities&lt;br /&gt;6. Comparison of ISS printed parts with those printed on Earth (dimensional and strength testing).&lt;/p&gt;