I consider it as working. I am using an "open" carriage from ABS to hold the extruder and PLA/PTFE profile mount underneath. Maybe a full PLA carriage may work, if not relaxed from hotend's heat. I changed the Y-axis also, but i have to experiment more in order to have the same results i saw with the X axis. This is the carriage for aluminium profile x axis, using this http://www.thingiverse.com/thing:171294 for the ptfe rail and simonious idler+motor holder. At Simonius profile ( http://www.thingiverse.com/Simonious/designs ) you can find the x ends for every set-up. It's a work in progress, as the carriage won't be printed really nice, but it is working. Although i have to print with it to be sure. bare: http://youtu.be/LfLTiiDKvbU with extruder: http://youtu.be/ERUOjpFenDY printing: http://youtu.be/T046ZFsfEGw It is not obvious but the carriage is sagging because of the wieght of the extruder and the tolerance at the carriage's mounting. Printed with ABS, leaves some ABS dust on the profile cause of the friction. Better is to split the model and print the profile mounts out of PLA. If you make it, don't be shy. Let me knowBetter wait for a better edition coming in a week or so. Otherwise Screw in 4 x 3mm Allen bolts, or 8 x 3mm if you don't have lengthy enough bolts. The plastic base can hold it in place.