first off, i wanted to make the mouthpiece holder. i noticed on the pax that the bottom was wider than the top. that taper was going to be annoying, but i recently found a cool tool in fusion 360 to help with that.
I measured the bottom width and depth. i made a rectangle of those dimensions. I used a 3d printed radius tool to measure the radius on the curve, and modeled that into the rectangle.
I then measured the height of the mouthpiece, i created a construction plane that distance off the rectangle i just made.
on the construction plane, i started another sketch and measured the width/depth of the top of the mouth piece. i added the radius to this as well.
I then used the draft tool to create a solid body between the two sketches that matched the taper of the mouth piece based off of the two sketches.
Next, i needed to make a negative of the mouth piece. I made a rectangle, and used the extrude tool to make a cube that engulfed the mouthpiece i just made.
I then went to the combine tool, picked the big cube as my body, and the mouthpiece as the tool. I chose cut as the operation. This removed the mouthpiece from the solid cube.
When i extruded the cube, i added some height above the mouthpiece that i was going to cut away with. I made a sketch of two concentric circles on the top of the cube after cutting the mouthpiece out (think like a 2d donut shape).
I chose the draft tool again, picked the top of the void in the cube (top of the mouth piece) and the area of the inner circle on top. I chose cut, which removed a nice rectangle to circle shape that would be impossible to model otherwise.
The sketch with the two concentric circles was then about to be returned to, but first, an intermediary step. i made a new sketch, but a side profile this time. i made a line that went up, then a curve that went 180 degrees. this was a construction line.
I returned to the sketch with the two circles. I chose the space between them (the pastry part of the donut shape) then used the sweep tool to sweep the extrusion along the construction line path i made this made that curve shape.
I then made the 14mm taper the same way as the mouth piece. It made a solid shape so i cut the air channel out with a circle, extruded up, using the cut operation.
I then added some champers / filets to make things look smooth
lastly, i did a cross section analysis to verify there was a completely empty air channel with no real thin blocking objects
i noticed the mouth piece bit was a bit thin at the bottom, so i made a cube with .25" height and used that to cut the bottom .25" from the mouthpiece.
export to stl, start printing, and tada!