Kind of, yeah, but I think that'd only be done when they just need a little more, not a huge boost in production. What if they need every machine they can get running 24/7 because it's critical for farming in a drought that could cause a famine, or because it's part of a weapon needed in a defensive war? Modern printers are slow and can take hours to print large objects, so maybe you're willing to wake up every couple hours overnight to start a new piece for a good cause, but what if the printers they need finish a part in only 30 minutes? Are they willing to trust such critical production to run without direct oversight when people might slack off? What if hobbyists can produce enough, but the logistics of shipping them from all over the US (just as a hypothetical, it's big and poses logistical problems) would put excessive strain on postal services or take way more work to properly coordinate? In low stakes scenarios, enticing people to contribute with pay may be sufficient, but when the tool and what it makes is critical, bigger steps may be viewed as necessary and within the authority of the state to take, and they might include confiscating the tools and redistributing them to directly increase production.