I made a quick and dirty box stl to run on my machine to wear in the pipes if anyone wants to use it. http://www.thingiverse.com/thing:1578631
You can scale it to your build plate. I set my slicer settings to 80mm/s with temp set to 0. I remove the filament from the extruder, or you could just unplug the extruder for the print. let it run and it’ll bump all 4 corners and infill a 5mm thick wall from corner to corner. it took about 15 hours on mine and when it was done, it had done a pretty decent job of removing a fair amount of plating from my conduit.