The Free Parts Library: Public-Domain 3D Parts and CAD Drawings

The Free Parts Library is a collection of 3D parts and CAD drawings that anyone can open in the browser, download and reuse. It starts with 758 files in two libraries:

• The Drawing Library has 623 drawings: 612 standard drawings from the USDA Forest Service in DWG, and 11 fully toleranced engineering drawings from NIST in PDF.
• The 3D Parts Library has 135 models: 124 furniture and fixture models from Kenney in GLB, and 11 machined test parts from NIST in STEP.

Every file is in the public domain. There is no account to create, nothing to install, and no credit required when you use a part in your own work.

What is in the Drawing Library

Most of the drawings come from the Forest Service Engineering AutoCAD Drawing Library, the standard details the agency drew for its own campgrounds, trails, roads and facilities between 1988 and 1999. They cover the things a site designer draws again and again: fire rings, picnic tables, bollards, gates, cattleguards, culverts, waterbars, retaining walls, boat launches and tent pads. There are complete building sets for vault and flush restrooms, pumphouses and fee stations, utility details for hydrants, manholes, water tanks and pump stations, and a set of recreation symbol signs (camping, picnic area, restrooms, trail use) that work well as CAD blocks.

The other 11 drawings are from NIST’s product manufacturing information test models: engineering drawings of machined parts dimensioned and toleranced to ASME Y14.5. They are a compact reference for GD&T callouts, datums and feature control frames, and each one has its matching 3D model in the other library.

What is in the 3D Parts Library

The 124 furniture and fixture models are from Kenney’s Furniture Kit: beds, sofas, chairs, tables, kitchen cabinets and appliances, bathroom fixtures, lamps, rugs and plants. They are low-poly with flat colors, which suits game prototypes, VR and AR scenes, and quick layout mockups.

The 11 NIST parts are real machined parts modeled as exact CAD solids. Open one in the viewer to rotate it, measure it, or cut a section through it.

Finding and using a part

Each library has a search box that looks at titles, descriptions and keywords, a filter by file format, and filters by tag. The tags describe a part (3D printable, real-world scale, dimensioned, organized layers) or what it is for (mechanical, architecture, floor plans, construction details, blocks and symbols).

Clicking a thumbnail opens the file in the 3D Viewer. Models can be rotated, sectioned and measured; drawings can be zoomed, measured and have their layers switched on and off. Each part also has its own page with the full description, tags, license and source, and a download button for the original file. To get a part in another format, open it in the viewer and use Export: a STEP part can come out as STL for printing, a drawing as DXF or PDF.

Licenses

Every part is in the public domain, under one of two terms, and its page says which:

• CC0 1.0. The Kenney models, and every part people contribute. CC0 is a public-domain dedication that works worldwide: use, modify and redistribute the file for any purpose, including commercial work.
• US Government work. The Forest Service and NIST files. Works of the US federal government are in the public domain in the United States (17 U.S.C. §105); the rules in other countries can differ.

The Forest Service drawings carry the agency’s own caveat: they were drawn as guidance for Forest Service projects and may not meet current standards. Treat them as a starting detail and check dimensions, codes and site conditions before building from one. The library terms have the full wording.

Adding your own parts

Contributions go through the same two libraries. The viewer decides whether a file is a 3D model or a 2D drawing, so there is one way in for both.

One file at a time: open it in the viewer, click Share, and tick Also add this model to the Free Parts Library. Give the part a name and a description, add a few search keywords, and tick the tags that fit. The contributor agreement confirms that you have the rights to the file and dedicates it to the public domain under CC0; the share button stays disabled until it is accepted.

Many files at once: the contribute page takes up to 50 files, or zip files of them. A zip is split into one part per model or drawing inside it, except when its files belong together (a glTF with its textures and buffers, a shapefile, a Gerber fabrication set), in which case it stays one part. Each file gets a thumbnail and is sorted into the right library, you describe each one, and shared keywords, tags and a credit line can be applied to all of them in one step. The agreement is accepted once for the batch.

Every contribution is reviewed before it appears. Parts are kept for a length of time that depends on file size:

Ordinary share links, outside the library, are kept for 90 days.

How the first collections were checked

Every file in the starting collections was opened in the viewer to render its thumbnail, and every thumbnail was reviewed by eye. 55 files were left out: blank forms and quantity tables, cover sheets, specification sheets for obsolete light fixtures, and modular floor and wall pieces that mean little on their own. Six more drawings are held back because their content sits inside nested blocks, which the viewer does not draw yet.

Opening several hundred real drawings and models also turned up rendering problems in the viewer, which are now fixed for every file it opens:

• DWG blocks with a base point draw where AutoCAD draws them, inside their sheet border, however far from the origin the block was defined.
• Older DWG files (AutoCAD R12 and earlier) now read entity thickness and place dimensions at their own insertion point and scale.
• A drawing opens framed on its content. Arcs are measured by their sweep, blocks by what they contain, and the odd stray entity far from the drawing no longer shrinks it to a speck.
• STEP faces with holes, drill points and countersinks are complete. On the NIST parts the surface area now matches OpenCASCADE exactly.

Browse the Drawing Library and the 3D Parts Library, or add your own parts.