3D Model Icon Generator generates icons when provided with a 3D model. This uses Blender from the command line to generated images of models to be used as icons or thumbnails, the idea being this ...

The file display is set to 'Extra Large Preview', but the contents of the 3D model cannot be seen, and the file icon and related application icons are displayed.

As the name suggests, Open 3D Model Viewer is a dedicated free and open-source 3D file viewer for Windows 11/10. In it, you can visualize 3D models of formats including 3DS, OBJ, PLY, DAE, STL, etc.