I took ppyromann's dust filter and modded it a bit. I split the top and bottom into two STLs to make it easier to print/reprint. I also scaled the screw cap filament tube to accept 3mm filament.
The RT tagged STL is the same 3mm screw end but the threads (just the outer threaded bottom area) were scaled down 0.5% in Modo. I was running into issues with the threaded pieces screwing together so this minor scaling fixed the problem.