The original wooden ones that came with my Makerfarm i3v were damaged by over tightening the screws that hold them in place, I tried searching for these online and to my surprise no one has designed them yet so I opened up 3ds Max and made them :) It is a very tight fit but with the right amount of force it will snap in real nicely. I printing mine at 0.3mm layer height and 50% infill with the model laying flat on it's side.