When you double-click on a file in Windows, it will automatically open a default program that is configured to manage these types of files. It is common, though, want or need to use a different ...

The most common reason an STL file may be not quite right is a mechanical connection where some piece isn’t quite as the designer expected, so the 3D model that interfaces with it no longer fits.

Right-click an empty spot inside the directory. Click Open in the terminal. Issue the command (including sudo) to open the file with elevated privileges. That’s a bit extra.