Maybe it's time to shelve the old saying, "you can't leave home without it," when it comes to packing for trips to space.
Say you're hunkered down inside Mars Base-1 and a vital piece of life-support gear breaks down. A hurried search in supply bins proves futile. The next cycler spaceship with equipment is months away. Time is running out.
This disaster scenario could be short-circuited by what's tagged as "additive manufacturing" — a process to fabricate or 3D print a critical widget layer by layer. Using additive manufacturing equipment, items can be cranked out on the spot, whether they're made of hard plastics or certain metals.