I was gifted a partial bottle of Radha tea tree oil without a dropper. I adjusted the dropper I had already made for 5 ml bottle to fit this bottle. I haven't tested it on a full bottle, but I'm guessing it should flow fine at the proper angle.

This dropper fits a bottle with 14.4 mm (inside diameter) opening. However, I have included the FreeCAD file for anyone that needs to edit it. Made a screen recording showing how to do that. Here is a link for that... https://odysee.com/@HOWIC:d/How-to-edit-dropper-cap-size:2

If one deems it necessary to extend the length of the vent pipe, that can be accomplished by altering the length of it in sketch 001 of the Freecad file. The one that is currently 26 mm. I made mention of it at 3:45 in the video linked above, but didn't explicitly state that would change the length of it.

For those that do not want to sign up to download this, I have made it available on my Odysee channel...
https://odysee.com/@HOWIC:d/dropper-cap-for-4-oz-bottle:6