If you are using OpenSCAD for your 3D model construction, and after creating a satisfactory model do an export to STL, you may observe that nothing at all happens!
I was stuck on this problem for awhile. Yes, the solution is obvious for a regular users, but I only use it every few months. If you open the console you will see the problem immediately:
ERROR: Nothing to export! Try rendering first (press F6).
But in my case I had closed the console, forgot there was such a thing, and of course it remembers your settings.
So you have to render your object (F6) before you can export as an STL file.
OpenSCAD is a 3D modelling application that uses CSG – constructive Solid Geometry. It’s very math and basic geometric shapes focussed – perfect for me. https://www.openscad.org/