How to find free STL files

What is an STL file?

An STL (for “Standard Triangle Language” or “Standard Tessellation Language”) file is one of the most common file formats for both 3D printing and computer-aided design (CAD). These digital files contain geometric information about a design that is meant to be 3D printed. In STL files, these designs are represented by triangles – hence “triangle language” or “tessellation language.” Because these triangles share edges, their location can be determined by a computer or slicing program (more on this below) to create a full image that can be 3D printed. The more complex the design, the more triangles are used to represent it. An STL file does not contain any information regarding texture, color, or qualities such as flexibility or strength – only the shape and geometry. Alternatives to STL files such as OBJ files, however, can store data related to color and texture profile.

How to use STL files

Once created or downloaded, STL files are generally exported into a 3D printing slicer, such as Ultimaker Cura. There, the STL file is converted into a language your 3D printer can understand “G-code,” which tells it exactly how to print a model or design. It is also possible to directly download G-code on certain websites like printables.com. This requires you enter your printer settings and configuration before downloading the file and does entail some increased risk, with the benefit of not having to manually slice the file.

Should you have the technology, STL files can also be created with a 3D scanner, which can scan an object and create an STL file from that scan. Most desktop 3D printing users, however – and especially beginners – will either download STL files from online repositories, or design their own using CAD or other 3D design software, depending on experience and use case.

Where to find free STL files

The internet is full of websites and resources for those seeking STL files. Some of these sites offer STL files for sale, others for free, and others still a mix of both. Below are five of our favorites.

• Thingiverse. Perhaps one of the most well-known repositories, Thingiverse offers a wide variety of both for-sale and free STL files. Its UI is clean and easy to use, and it contains thousands of user-created designs and models, which run the gamut, from toys to tools

• Cults. Cults hosts a large variety of STL files, sorted by category, including architecture, gadgets, games, tools, and jewelry. If you’re looking for a file in one of these areas, chances are you’ll find it on Cults

• Free3D. Free3D is all about – you guessed it – free 3D files. Not all are STL files, but that doesn’t mean there aren’t plenty to choose from. Here, however, you’ll mainly find STL files geared towards hobbyists or more casual 3D printing users. If you’re looking for professional applications, you may need to look elsewhere

• STLfinder. STLfinder lacks the polished overview of other sites out there, but its simplicity is a benefit. Just type whatever you’re looking to print into the search bar (essentially the only thing populating the home page), and you’re good to go

• Yeggi. Yeggi is similar to STLFinder, in that it functions predominantly as a search engine for free 3D design and STL files, of which it is home to more than 2 million. Unlike STLFinder, however, searching on Yeggi is a slightly more refined experience, thanks to filters and other options that enable you to better home in on exactly what you’re looking for

• Printables. Formerly known as Prusaprinters.com, Printables is one of the fastest-growing STL file repositories. In addition to thousands of downloadable files, the site also has great community engagement, and regularly runs contents to discover and spotlight amazing 3D designs

• MyMiniFactory. MyMiniFactory caters predominantly to tabletop miniatures and terrain. It offers a great number of free files, although creators are also able to sell their designs – enabling them to pursue careers as full-time 3D designers

Still haven’t found the right STL file? In addition to those listed above, here are several other popular websites that host free STL files.

• Sketchfab

• GrabCAD

• NIH 3D Print Exchange

• YouImagine

• 3DWarehouse

• 3DShook

• Pinshape