Berp is famous for it's buzzing extension. Instead of paying for their $15-$20 piece of plastic, here is a different design based off a different company's buzzing extension. Goes straight into the lead pipe, mouthpiece fits in the other end. I had some problems with the calibration of my printer, since all needs to be perfect. You may need to scale it up a few percent. Either way, the Autodesk Inventor 2015 .ipt file is uploaded. (Free 3-year trial for students) Might add a resistance piece sometime.. The outside diameter of the cylinder for the mouthpiece should be 15.7mm; the inside should be 11mm