STL thumbnails in Windows Explorer

What you see

• Each model is rendered flat-shaded from the same three-quarter angle, on a transparent background, so a folder of prints is easy to tell apart at a glance.
• Huge scans with millions of triangles are drawn whole, triangle by triangle as the file is read, so they never have to fit in memory.
• Press Space for the same rendering at full size in Quick preview, or look at it in the Explorer preview pane.

Limits

• It is one fixed view of the plain geometry, not a slicer preview: no supports, layers or print settings are shown.
• In OneDrive and other synced folders, files stored on the PC get thumbnails as anywhere else. Online-only files are left to the cloud app, since nothing is downloaded just to draw a thumbnail.

More you can do

• Sliced files show the picture your slicer saved in them: see G-code and 3MF thumbnails.

Extensions this covers

See every format SageThumbs 2K supports or browse all format guides.

Thumbnails not showing?

• Windows caches thumbnails, and a file it failed on once stays failed. In SageThumbs, Settings ▸ Advanced ▸ Rebuild thumbnail cache clears the cache and restarts Explorer.
• Make sure File Explorer's "Always show icons, never thumbnails" option is off, and that the format is ticked in SageThumbs Settings ▸ File types.
• Run st2k doctor in a terminal. It only reads, checks the whole chain, and prints a fix under anything that is wrong.

Related guides

• G-code and 3MFSliced prints and 3MF projects, from the picture the slicer saved.
• OBJ and PLYMeshes from 3D apps and 3D scans, rendered shaded.
• Fusion 360 .f3dFusion 360 archives, from the preview packed inside.
• Blender .blendBlender scenes and their numbered backup files.