I have posted another video to explain the function convert_3lines2fillet. a few of you might find it useful. Now the library name is changed to openscad2.py As per my understanding many complex fillets can be modeled with this library, if you have the understanding of various functions. I also think the "bspline" function which I have written in openSCAD as well is very useful and can be used by people who are more comfortable in pure openscad. It is available in the library "dependencies.scad" and has a much wider application. https://youtu.be/kDwPzkyExm4?si=0KXJZWXTsefot_mA