Our Lab's 3D printers (MakerBot Replicator 2s) are amazing machines and have been used to create lots of cool and useful objects. However, their stock extruders (i.e., the component that feeds the filament through the nozzle) are quite sensitive and require a good deal of care and attention. We are addressing this challenge by upgrading to a newly designed extruder (see: http://www.thingiverse.com/thing:53125). However, rather than ordering this upgrade from a store, our printers are actually printing it out. That's right, our printers are making their own parts! This self-replicating aspect was one of the founding principles of the Rep Rap Movement nearly a decade ago, which kicked off the desktop 3D printing movement (http://en.wikipedia.org/wiki/RepRap_Project). Just like your smartphone uploads firmware upgrades, our 3D printers upload hardware updates!