UM2 nozzle jam after 3 layers after material change (w/ pics) in Ultimaker 3D printers Posted June 26, 2015 Also I wouldn't call doing atomic pulls strictly plug n play. I found that I had to learn how parts of the printer works for it to get the result i wanted, and theres noway i would have known without tinkering. After building a RepRap from scratch over 4 years ago with very little calibration and troubleshooting documentation available online, and the machine taking over a year and a half to get a decent print, being able to take an UM2 out of a box and have it print a very nice octopus after 45 minutes of setup is pretty plug and play in my book. True they still need a lot of tweaking, but having a machine that works out of the box and needs some maintenance from time to time is better than starting with a box of parts. We have a couple Stratasys printers here, so some of the engineers should be able to deal with it when little problems arise, I just needed it working by the time I left. But yes, when it comes to the everyday, non technical user, these are still far from plug and play without hassle.