LifeStraw back flush adapter (for older model Straws)

I pushed the mouth of my LifeStraw into an ink pad.
Then I stamped a piece of paper with the inked mouth, leaving a black outline of the lip of the spout.
Then I used my camera with a slight telephoto (to minimize parallax) to take a photo of the outline. (Using a flat bed scanner would be best.)
Then I imported that photo into FreeCAD to make a reference image.
I calibrated the image.
I traced out the left half of the image using B-splines.
Then I hacked my way through making a mirror image of the left half of the points to make a symmetrical mouth.
I padded that to make a model for a “hole” that I could Boolean out of the original Adapter.
I exported the pad to an .stl. (Included.)
Then to Blender.
I imported the original Lifestraw Back flush Adapter into Blender.
I Boolean’d a cylinder to fill in the existing hole of the Adapter.
Then I imported my FreeCAD stl model of the “hole.”
I tapered the “hole” using Bender’s Simple Deform.
I boolean’d it out of the original Adapter and made some test slice prints to test for fit. I adjusted/iterated the scale and the taper of the “hole” as needed.
After a good fit, I added some cylinders, tapered them, and boolean’d them out of the sides of the Adapter to give it more grip. (I printed in PETG, which tends to bind on plastic bottles.)
Last, I used Blender to taper the inside coupler a bit. (I used the “Push/Pull” Edit tool.)
Export to stl.
Clean up the stl in Orca.