This thing is a trombone mouthpiece with boatloads of parameters. It can be customized in customizer. You should be able to reasonably approximate more or less any rotationally symmetric mouthpiece out there. I mostly use my printed mouthpieces for warming up in the car on my way to rehearsal. On the bass trombone, I find that printed mouthpieces are extremely warm sounding, almost Euphonium-like. The default parameters will give you something vaguely resembling a 4G size mouthpiece. Updated: 2013-03-30 with a new set of parameters for improved cup geometry based on an analysis of several commercial mouthpiece curves. Updated: 2013-04-13 with improvements to the outside geometry and a couple simplifications to try (unsuccessfully) to make it work with customizer. OpenSCAD reports that the file compiles to a valid, simple 3D object, but customizer is unable to generate an STL file. However, you can always download the scad file and edit it with OpenSCAD.Brass-instrument mouthpieces are subtly complicated objects, with many distinguishing features that are at or beyond the resolution of current consumer printers. But it's still pretty cool to be able to print your own, even if it's not going to replace your fancy Greg Black.And they're hard to print. If you could print them rim-side down, it'd be a lot easier. But then you have to print with a flat rim and manually apply all of the subtle shaping that makes a rim comfortable and well-playing. Plus, the interior slope on many cups would exceed 45deg at some point. So, it's best to print the mouthpiece with the rim-side up, but that presents other challenges.The current design defaults to printing the cup/rim and shank in two pieces, in an attempt to make it easier to get a successful print. I use bezier curves to define the shape of the cup and of the rim. I chose the control points by eyeball. The outer shape of the cup is mostly determined to be printable without support, at least if you use a non-pathological set of parameters.The trick is getting a nice smooth finish, especially on the portions of the rim that contact your face. For best results, I print in ABS at 0.1mm layer height, then sand lightly before putting the mouthpiece in a rice-cooker acetone vapor bath. I'm still working out the optimal vapor-bath procedure. The shank is fairly fragile, and it's easy to overdo the acetone and melt your mouthpiece.If you print the cup only (see the Printer tab in Customizer) with a large-shank, it should be adaptable for use with a Doug Elliott shank. When the mouthpiece is still slightly soft after it has been out of the vapor bath for an hour or so, you can carefully thread the Elliott shank into the printed cup. That's not a bad way to go if you've got an Elliott shank.