The most popular design file format is the STL file. And although it’s not very tricky to create high quality STL files for 3D prints, it’s not easy as well.

Find out what is an STL file and how you can open and view an STL file with .stl extension in Windows 10. It is native to the stereolithography CAD software.

If you want to create a 3D model in STL format or edit an existing STL file in Windows 11/10, use these free STL editors.

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.