the patent expires this year, if it hasn't already.
Oh FFS. In order to get sued, someone with a financial interest in the design would have to be trolling forums like this looking for anyone who is violating their patent. What do you suppose the odds of that are? I think you're more likely to be killed by a lightning strike. You would no doubt receive a cease and desist letter from a lawyer before anyone filed a law suit.
Don't worry about patents unless you're trying to sell the stuff you extract from someone's patent, and even then I think they have to prove financial harm as a result of your activity. The patent document itself discloses the shape of the horn for everyone to see, as does the product itself.
I'm pretty sure anyone filing for a patent on a horn is going to have some engineering justification for the specific shape which would be the real IP of the patent. You're just using ellipses to make something that resembles a properly designed horn.
I design and 3D print stuff all the time for the last 14 years or so. I have never once concerned myself with patents, though I have probably violated a few during that time- but how would I know? If you had to worry about patent violations every time you designed anything, you'd spend all your time doing patent searches and no time designing anything. Forget about patents, except as a source of information/inspiration. That's what the patent documentation is for.
When I designed and built my 3D printers, they had heated chambers before the Stratasys patent on heated chambers for 3D printers expired. I didn't care about their patent. I needed a printer that would print ABS without warping or delaminating, and I sure wasn't going to buy one from Stratasys, so I built it. And it worked. And I posted my design info on line. Patents schmatents.