Here is how to configure the STL Shell extension:
Windows File Explorer has somthing called ShellExtensions that makes it possible to create a small “thumbnail-image” of the content of a file.
Many companies that have propierary formats create shellextension for ther data-files.
STL (STereoLithography) is a file format native to the stereolithography CAD software created by 3D Systems. STL has several after-the-fact backronyms such as “Standard Triangle Language” and “Standard Tessellation Language”. This file format is supported by many other software packages; it is widely used for rapid prototyping, 3D printing and computer-aided manufacturing. STL files describe only the surface geometry of a three-dimensional object without any representation of color, texture or other common CAD model attributes. The STL format specifies both ASCII and binary representations. Binary files are more common, since they are more compact.
An STL file describes a raw unstructured triangulated surface by the unit normal and vertices (ordered by the right-hand rule) of the triangles using a three-dimensional Cartesian coordinate system. STL coordinates must be positive numbers, there is no scale information, and the units are arbitrary.
( Wikipedia https://en.wikipedia.org/wiki/STL_(file_format))
This is the story about the development
I could not find any STL Shell Extension so I start develop a small and fast STL-ShellExtension for Windows File Explorer. After 3-4 month I understood why ther was no good STL-ShellExtension. The fact was that it was very complicated to make this both fast and small.
The first attempt was to create a STL-Viewer to get a image from the triangles that STL consist of.
When this was done the next thing was the creation of a Shellextension that uses the image scaled to a thumbnail. In the beginning I tried to do this myself. I got problems with different versions of Windows. Then I find and paid for a component, EZShellExtension.Net v2013 that solved the problems with creating a ShellExtension.
( http://www.ssware.com/ezshell/ezshell.htm )
After 9 moth of development the first STL-ShellExtension was almost finished. The thing left was to get it working fro different Windows version. I belive now it is possible to run this on Windows 7 to Windows 10.
There will not be a Apple/IOS or Linux version. The approach for this is totaly different and I belive this is as complicated as it was for the Windows OS.
After installing the STL-ShellExtension the Windows File Explorer needs to be cleaned of old existing thumbnails. This is a painful operation. Actually, you have to delete all thumbnails for all formats. The thumbnail file is not big, but it takes some time to recreate. That is why there is a progressbar in a Windows File Explorer frame first time you enter a directory that contains file(s) without thumbnail(s).
As a 3Dprinter entusiast you have 1000+ files and this will take some time.
The STL viewer was polished to become something I bundled into Marlin3DprinterTool. It has nothing to do with Marlin Firmware but it was small and fast and helped me when I was debugging. It also make life alot easier then I wanted to get a closer view to a STL file. Faster than starting up some other software.