Free3D is a marketplace that offers a decent selection of 3Dmodels. Unfortunately, not all of the models available here are STL files, but some of the other formats (such as OBJ) are also compatible with 3D printing software.
You can browse models by categories, such as electronics and vehicles, and even upload your own models and show off your skills!
On Pinshape you will find both premium and free models that are designed specifically for printing. There is also a wealth of useful information on 3D printing that makes it an excellent site for people who are new to the scene.
If you are a maker of 3D models for printing, you can share your work here as well. You can even receive financial compensation for your models.
Rather than a repository of STL files, Yeggi is more like a search engine. Using Yeggi, you can run a search on several different platforms across the Internet, filtering your results to suit your needs.
Yeggi returns both free and premium models, although you can filter it to just return paid models. Yeggi is quite possibly the most popular destination for 3D printing models, so you know you're in good hands.
Another very popular site is Cults. Cults has a wide variety of models, from architectural to fashion pieces. There is also a social component to Cults, allowing users to chat with each other and generally nerdout over their love of all things 3D printing.
For creators, there are contests for you to enter. The people behind Cult also keep up an impressive blog schedule, regularly posting new content for their users.
Set up with the goal of bringing designers together, MyMiniFactory is full of free files intended explicitly for 3D printing. It is a marketplace, so not everything there is free, but there is plenty to choose from in the free category.
There is a blog full of great content for 3D printing enthusiasts, and even a service for requesting models from professional designers if you can't find the thing you need on the site. One particularly interesting feature is its "Campaign" service, which is a crowdfunding platform similar to Kickstarter, but specifically for 3D printing models.
Similar to Yeggi, STLFinder is a search engine rather than are pository of 3D models. In terms of additional features, STLFinder isn't quite as impressive as the other services on this list, but that is part of its charm. It does exactly what it says in the name.
Similar to the Google homepage, you are presented with nothing more than a search box. Enter the thing you're looking for, and STLFinder will go hunting through the web for you. The results are neatly arranged on the STLFinder website, making it easy for you to browse through and find what you're looking for. The front page even shows you some of the more popular search terms.
SketchFab is not strictly limited to 3D printing. Indeed, it is particularly popular among the game development community. Still, files can be uploaded in several formats-including STL-making it just as useful for 3D printing enthusiasts. Just be sure to filter your searches for STL files.
A nice feature of SketchFab is the ability to preview 3D models on the website using their built-in 3D preview tool. Many of the models on this site are not free, but there are plenty that is if you search for them.
Brought to us by the people behind Sketchup-a popular 3Ddesign application. 3DWarehouse is primarily aimed at professionals, and exclusively for models created using the Sketchup application. Still, there are plenty of goodies for us 3D printing enthusiasts.
It is worth noting, however, that while this site is a good source of free STL files, its focus is on other things. Don't expect to find much help geared towards 3D printing on here.
As you'd expect from a site founded by Makerbot-one of the pioneers of the 3D printer space-Thingiverse is heavily geared towards 3D printing. You will find the majority of the STL files on here are free. You can also contribute to this impressive pool of models if you are a dab hand at 3D modelling.
Thingiverse encourages interactions between users, such as giving opinions on models. There are over 1,700,000 files to choose from on Thingiverse, so there's a good chance you will find what you need.
Geared towards CAD (computer-aided design) as a whole, GrabCAD has one of the largest selections of CAD models around. There is a considerably more professional feel to the site, with engineers, architects, STEM students, and generally professional people making up its typical user base-a user base that is approaching six million people!
With around four million free files at your disposal, GrabCAD is easily one of the largest sites of its kind online.
That's our list of best websites to download free STL files, but it is far from a definitive list. There are plenty of resources for what is still a young market and growing all the time.
And, if you get the urge to make your own models, there are plenty of options for sharing them with the 3D printing world.