Parametric Acoustic Horns
by thehans, published
This is a python script for use with FreeCAD, which is capable of generating various horn-like profiles, for experimenting in acoustics, or just for making a fancy funnel.
I tested a horn as a cellphone amplifier, with pretty decent results.
Put the script in your FreeCAD macro directory. Edit the call to Horn function at the bottom of the script to suit your needs. A mesh will be added to the freecad document, which can be exported to STL using the Mesh menu.