Yes, melting plastic in a closed environment. Brilliant. Instead of planning for their little hobby-jump in Low Earth Orbit, let's bring a cranky, tiny toy to make coat hangers... (in free-fall LOL). I just love the armchair engineers and programmers here going on about the 3D printer will be this tool to help colonize the universe..
I never said that it would help colonize the universe.
I expect that it'll be useful when that plastic tab on that rocker switch that's used all of the time breaks off, so they an print themselves a replacement instead of waiting weeks or months for a resupply mission to bring them one, or when an astronaut realizes that a particular control stick or other device is causing skin abrasions, so they could design and print a different one that doesn't cause sores, or any of a whole set of times when a spaceman needs some small, insignificant-on-earth part that is literally worth its weight in gold because they just don't have access to it.
I could even see circumstances in an Apollo-Thirteen kind of accident where engineers at NASA could come up with a fix that's safer and more reliable than duct-taping some plastic sheeting to a bulkhead because the tech to manufacture a few parts exists with those that need those parts.