After the success of my first printable extruder design (the Printruder, see http://www.thingiverse.com/thing:958 ), I wondered, if there would be an even simpler and better design for a Printruder.This is what I came up with.Please note, that there are two flavors of the main part ("Motor Block"):You only need one of both. Be sure to print the correct one!The PCB holder parts are optional.There's a post on my blog on this with more detailed information and step-by-step build instructions: http://pleasantsoftware.com/developer/3d/2010/03/08/printruder-ii/In order to mount the Printruder II in a MakerBot, you might want to print also a pair of Printable Extruder Holders: http://www.thingiverse.com/thing:1912