Curt Hall takes a look at the role 3D printing can have in space exploration. From Earth-based manufacturing of spacecraft parts to tools like wrenches on the International Space Station and metal parts during a Mars mission, space could be 3D printing’s killer app. Hall discusses a large number of technologies in development, including the ability to convert plastic waste from previously printed parts into feedstock that can be used to create new tools and parts. Similarly, there are projects underway to see if the Moon’s regolith can be used to construct the (literal) building blocks for a moon base. Printing food, medicine, and even replacement organs for long-haul space missions is also being explored using bioprinting, a technology that could come full circle to provide tissue-based patches for the outside of damaged hearts here on Earth.