I left my #Prusa 3D printer unattended for a couple of hours, and it completely screwed up and the extruder got completely encapsulated in a 1cm thick glob of PLA filament. This is what it looked like after half an hour of delicate unglobbing. Another half hour of cleaning and reassembling and it was working fine again. Not sure what went wrong - PETG builds are nearly always perfect, but I'm building something that should be a little more flexible, hence the PLA.
