The major benefit of a bowden printer is having a very lightweight hotend that You can swing fast and free. I've designed this specific part for my reprap that can run over 250mm/sec and not lose a motor step. this part holds the 16mm J-Head firmly and keeps the nozzle exactly in place.make sure You measure Your J-head for an outer diameter of 16mm and inner of 12mm (see the blueprints).After upgrading my machine with this part the prints are smoother, more precise and also repeating precision has increaced.I'm adding the Inventor design file if You like to tweak the model.Printing recepie: I've printed the part in 0.25mm layers and if works fine, but for best results keep the print layer about 0.2mm.most of the torque is on the skin, I suggest a wall thickness and top/bottom thickness of at least 1mm.I've printed without an infill to keep the wight below 8 grams, You could add an infill but don't go over 15% or over 15 grams for best results.almost any material should do the job. I suggest PLA.If You have any questions keep in touch :)