I hope this is on topic enough for this forum. I use what I’m about to share more for 3D printing but it is about making STL models so I thought I would share it with this forum because I like you all.
I have used OpenSCAD’s customizer to generate STL files of some metric threaded parts.
OpenSCAD is a programmers CAD application. You write code to make models but the cool thing is that OpenSCAD has a customizer where the programmer, that’s me, can write all the code and expose variables in a User Interface that are used to change the model. So that means you don’t need to do any programming to use this and OpenSCAD is free.
Here is an pic of some of the stuff it can make.
You can make nuts, bolts, and threaded rod in I think 63 or 64 metric sizes ranging from M2 to M100.
In the download there are 2 files. One is a PDF with instructions that will help you if your not familiar with OpenSCAD and the other is the dot scad file that you open with OpenSCAD to use the generator.
BaNG Metric.zip (107.7 KB)