This is a bowden extruder mount that fits the Alu-Extruder from Printrbot and mounts to an earlier rail design of mine that spans the top of the printrbot plus. Takes 2-4 M3 screws and 1 #6-32 (screw and nut). I didn't tap the hole for the bowden connector, I got lazy. I'll need to go back and put that in as it would require some glue without the threads to hold it there. Also I think it will operate better if I turn it sideways so it feeds filament in the back and out towards the front of the printer. I'll leave it as a thing in progress until I add those parts, but it works fine as is minus the glue so here it is.