I recently built a printer designed roughly on a Prusa i3. I managed to get a few prints out of it (about 18 hours of printing time) and flipped the direction of the Y axis because I realized my parts where a mirror of what I was sending. I am using repetier as my host and firmware, so I went back into their configuration tool and uploaded my previous configuration.h file and only changed the dby thatstaken - Reprappers