ThumbHost3mf

ThumbHost3mf is a macOS application that installs a Quick Look thumbnail provider for files containing embedded preview images, specifically .gcode, .bgcode, and .3mf formats. When the app is placed in /Applications and launched once, it registers the plugin so that Finder can display the embedded PNG, JPG, or QOI thumbnails instead of generic icons. The provider reads thumbnail data that slicer tools such as PrusaSlicer, Bambu Studio, or Orca Slicer embed near the start of the file, and it supports thumbnails stored as base64‑encoded PNGs or as separate metadata files inside .3mf archives.

The software is aimed at users who work with 3‑D printing and CNC machining files on macOS and want visual previews directly in the file manager. It is useful for anyone who generates or edits gcode, bgcode, or 3mf files and wishes to identify them quickly by their content rather than by file name alone.

Key distinctions include native macOS Quick Look integration, support for multiple thumbnail formats, and a simple one‑time registration process. The app runs on macOS 10.15 and later, and it provides an optional setting to label icons with their file type.