What is filament?

Filament is a native macOS app that adds proper thumbnails and interactive previews for 3D printing files, so you can select a model file in Finder, press the space bar, and see it spin in three dimensions without opening a slicer program first. It supports the common 3D printing and modeling formats: 3MF, including multi plate Bambu Studio and OrcaSlicer project files, along with STL, OBJ, and PLY. The app generates near instant thumbnails in Finder, using the slicer's own embedded plate image for 3MF files and rendering the others on the fly. Pressing space opens an interactive preview where you can orbit, pan, and zoom the model under soft studio style lighting. For 3MF files that use multiple filament colors, Filament renders the model in its real slicer colors, with an option to switch to a plain neutral look instead, and if a 3MF project has several build plates you can browse between them. It also shows basic model information such as dimensions in millimeters and triangle count, plus print time, weight, and printer details when a 3MF file includes them. Double clicking or dragging a supported file opens it in the full Filament window, and the app is built to open very large, multi million triangle files in about a second thanks to a dedicated streaming parser. It runs entirely offline with no network access or telemetry. To use it you need macOS 14 Sonoma or later. Building it from source requires Xcode and a tool called XcodeGen, and an included install script handles checking prerequisites, building a release version, signing it so it can run locally with just a free Apple ID, and registering it as the default viewer for 3MF and STL files. The project is organized as a dependency-free Swift library that does the actual file parsing and 3D scene building, a SwiftUI app that hosts the viewer, and two small Finder extensions that provide the thumbnails and the space bar preview. It is released under the MIT license.