On an orbiting facility, like the space station, you get some other benefits... * assuming theres also a filament extruder package (more initial weight i know)

On an orbiting facility, like the space station, you get some other benefits... * assuming theres also a filament extruder package (more initial weight i know), you can recycle the printing material some number of times, meaning that you can just not ship a bunch of custom things with each subsequent experiment package. * Materials can be better packed. Weight is an issue, but so is volume. A roll of filament can produce a bunch of parts that no longer need to be designed and manufactured to withstand "unfolding" stresses - you can just make the awkward shape in situ. * Related to the previous point - some things can be manufactured with much less material - they never need to handle 1g environments, let alone the vibrations and higher g parts of launch. This means less material in a lot of situations. * I presume (if there isn't now) there will be "rough" launches to carry bulk materials, and "gentle" launches for delicate things and people. If there is a way to do "rough launches" cheaper, (higher g, higher vibration, more risk since there aren't humans or super expensive equipment on board) then you can provide more space on the "gentle" launches for the the delicate equipment. Further - with more space on "gentle launches" you get a better iteration time, you don't have to schedule space/weight for your 3d-printable parts as tightly. Basically - 3d printing in orbit provides a nice way to separate several logistical concerns, easing some of the expense and engineering needed per experiment in space.