Digging through "free" sites to sort the "free beer" from the "free speech" content is quite a chore. Many of the sites are not useful for free culture projects, and many make it very difficult to tell. Fortunately for you, I took notes! Here you will find 8 sites with free-licensed content, 8 more with licenses that you'll probably find acceptable for many projects, and 20 others that might be useful on some projects if you're not a purist. There are also 22 sites I have to warn you away from, because their terms are incompatible with use in free-licensed productions.

Recently, I read a list of "60 Excellent Free 3D Model Websites". Like most lists of this type, it turns out that the word "free" doesn't really mean "free" for most of the content. So some fact-checking was in order.

Digging through these sites to find licensing terms is a major headache, as they quite frequently hide or omit this information

Digging through these sites to find licensing terms is a major headache, as they quite frequently hide or omit this information, but with a long list of needed 3D models that I don't really want to create custom, I'm going to have to figure out which sites are clearly usable, which ones I might consider compromising on, and which ones are absolutely unusable for us.

As long as I'm doing that, I might as well share the results!

I took the original list and added a few sites I already knew about or found along the way. For each, I searched the site for the license terms (this varies from easily pasting text off of the front page to searching vainly for a non-existent notice and finally giving up). I then categorized these according to three major criteria:

• Can we release derivatives under By-SA with the rest of the source tree?
• Can we share the models at all (with users or for collaboration)?
• Do the terms interfere with the By-SA terms for the final animation?

For each, I searched the site for the license terms

Of course, I probably should add the disclaimer that "I am not a lawyer, and this is not legal advice". If you want someone else to blame if you hit problems, you'll have to hire a lawyer. Certainly you should read the terms of any given site yourself before using the content. All that said, though, I hope you will find my categories helpful.

CC free licenses or public domain (6 sites)

All content on these sites is "free" in the sense of "free software" and all of it is compatible with re-release under a "Creative Commons Attribution-ShareAlike" license. These are by far the best sources for a free culture project.

• Blend Swap (blend)

Only models under free Creative-Commons licenses (CC-0, CC-By, or CC-By-SA) are allowed on this site. That makes it extremely useful for free-culture projects. If you're using CC By-SA license on your work, you can use anything on this site:

Blend Swap uses the Creative Commons license system. We’ve decided to use three licenses for all the models on Blend Swap, We’ve done this to keep licensing as simple as we can on the site while still offering authors a variety of ways to distribute and protect their art.
Creative Commons Zero Mark (CC-0)
Creative Commons Attribution (CC-BY)
Creative Commons Attribution-ShareAlike (CC-BY-SA)

• NASA 3D Model (3ds)

This is a small collection of models of spacecraft. Most are US spacecraft, but since the USA is cooperating with Russia on the International Space Station, the site also includes a few Russian spacecraft.

By law, information products produced by US federal government employees in the normal course of their duties are "copyright free", which is essentially identical to "public domain".

• Open Game Art (blend)

This is a collection of many kinds of art -- much of which is commissioned by the site maintainer, using donated and personal funds. All of the content is available under free licenses, including GNU Public License and Creative Commons By or By-SA, or assigned to the public domain. Most (but not all) of the content is low-polygon count, optimized for use in games.

• CGI (3ds)

Appears to be a very small collection, but really free:

All 3d models are free for any type of use (c/p). The version one is collection of very useful and handy 3d models in .3ds format. We will add more 3d Models to the collection, as time allows. Free 3D models are downloadable through our website in .zip format. Please click on the images to download that particular 3d model.

• The 3d Archive (q3o)

Site is non-commercial and donation-supported. The file format is unusual. Assigned to or asserted to be public domain:

All 3D files available from the3darchive.com are from the public domain. Whenever possibe, the original authors are listed on our Author's Page.

• Render Light (max)

Very minimal license statement:

The content showed here is of Free download and it has enterely been made by our staff. Feel free to use it in your creations yet if you want to credit us and let us see your work we will be happy. Enjoy!

CC license compatible, searchable by license (1 site)

These are almost as good, since you can simply set the search parameters to use the site as a source for free-licensed files. There was just one such site in my search, but it's a good one:

• ShareCG (TGO, 3dc, 3ds, max, AM3D, dwg, blend, brX, br5, obp, car, jas)

Has a nice advanced search widget for searching by license and category. The "unrestricted" license is compatible with conversion to CC-O or "public domain", and the "limited use" license is equivalent to "CC By" (i.e. the limitation is that the work must be credited).

The site also includes a substantial amount of standard "royalty free" work which can be used in renders, but not redistributed.

CC licenses, but not searchable by license (1 site)

Searching for free-licensed models on these sites is tedious work, because you have to filter out the non-free works manually, but there are free-licensed, Creative Commons-compatible models. The free content can go into our regular By-SA licensed source tree.

• 3DVIA (3DXML, kmz)

From the FAQ:

We have chosen to let users publish their 3D models under "Creative Commons Licenses" [...]

Allows commercial redistribution of model with source (8 sites)

In this category, I'm listing sites which will allow the models to be used royalty-free to create rendered animation under Creative Commons licenses, and which will allow us to include the models in their original or modified form along with the project source code. However, the licenses on the models themselves are generally not compatible with Creative Commons, and will have to be kept in a separate "non-free" category (because other limitations exist -- typically on creating a competing aggregate site).

The ability to redistribute the models is really important for a free culture project, not just as a matter of principle, but also because our open, online collaboration process is technically a form of redistribution. So we can't legally collaborate on works that don't allow this kind of redistribution.

• Telias (3ds, poser, md2, lwo)

Excerpts:

...everything you download from here is free for any use EXCEPT it cannot be included in another free web or cd collection and it cannot be sold separately. Otherwise you can use it in your commercial game, 3d application or render work. You don't have to provide credit but It would be nice if you do.

• 3Delicious (max, 3ds, gsm, lwo)
• Archibase (3ds, dxf, max, dwg)
• Archive3D.net (gms, 3ds)

These three sites, though apparently unaffiliated, use exactly the same license text (including misspellings):

This model may be used in any commercial way only if it is a part of artwork or project. Single reselling or redistribution of this model is prohibited.
[...]
This model may be freely modificated or elaborated.

• Google 3D Warehouse (skp)

Pretty free, except for the odd format, and the prohibition against aggregation. It also looks like you need to avoid using "Building Maker", which has more restrictive terms:

For the avoidance of doubt, you may modify, distribute, and create derivative works of Content uploaded by other users in 3D Warehouse.
[...]
you may not: (i) aggregate Content obtained from Google Services for redistribution, or (ii) use or distribute Content obtained from Google Services in a mapping or geographic application or service

• Oyonale (POV-Ray, C4D, Obj

This is a single artist's site. The license is brief but fairly clear:

These objects are freely usable for your personal or commercial 3D art and animations. The 3D models are available in POV-Ray, Cinema 4D and/or Wavefront OBJ formats.

Presumed to allow redistribution within sources

These sites are not as clear about their terms, but as I read them, they imply that distributing the models within the source code for the project is acceptable (as it would be for a game). They lack any demands for extraordinary measures to prevent access to the models (which some other sites require).

• Top 3D Models (max, 3ds, obj)

The explicit mention of games implies that the models themselves can be incorporated:

All the products the user will find on top3Dmodels.com are ready to be used in animations, games, or still renderings.

• 3DXO (max, 3ds, dxf, lwo)

Many of the models are listed by the uploader as simply "free" (as opposed to others which are "free for private use"). That appears to override the default license.

• DLegend (3ds ,max ,prj, obj, mb)

Says nothing to restrict the use of the "free" files, but the license is extremely unclear:

we have a collection of 3ds ,max ,prj and obj files for you to use in diffrent applications of 3d programs

Allows limited redistribution of models (2 sites)

These works cannot go into our distributed source tree, because that would probably constitute "commercial use", since we will deliver sources along with the movie. However, it might be possible to keep these in a special, password-restricted repository for collaboration use only. I think that's kind of ugly, but it would appear to be legal.

Of course, renderings of these works may still be released under the Creative Commons By-SA license.

• 3DXtras (max, 3ds, c4d, dwg, obj, mb)

The prohibition on commercial use appears to be limited only to competing aggregate collections of models for separate use, rather than collections targeted for a particular project (as in source code).

Relevant excerpts:

All the 3d models meshes, scenes and graphics in this website are not copyrighted unless stated.
You are free to use these models in your projects to generate games, animations, multimedia, printed graphics, web graphics and others.
However you are prohibited to resell, create your own license to give away these 3d models individually or as part of collection or bundle to get profit.

Commercial (transformative) use is explicitly allowed:

Our 3D models are 100% free royalty which you can use in any of your work and even your commercial projects.

• Exchange 3D (blend, max, 3ds)

This license insists on protecting 3D model content when it is incorporated into "pre-rendered productions" from being accessed separately by "end users":

Every effort must be made by the third party to protect the 3D content in a pre-rendered production environment. If the content can simply be removed from the production by the third party’s end user, this breaches the terms of this agreement.

Allows animations to be distributed under CC By-SA (18 sites)

These are the "royalty free" model sites -- and they are by far the most common type of resource.

They are awkward for a free culture project, because their terms (designed apparently as an anti-competitive measure against rival commercial repositories) interfere with our ability to work collaboratively on the project.

To fully comply with the licenses on these sites, we'd generally have to avoid any situation where more than one person works on a shot. Nevertheless, there are situations in which that might be feasible, and we'd have to weigh that against the cost of the duplicated labor in creating our own models.

• CG-Files seems to just be a portal for Buy3D.net (max, 3ds, pz2, pp2, obj)
• Top3D (max, c4d, 3ds)
• Toucan (3ds)
• Infinitee-Designs (max, 3ds, xsi, zbrush, blend, obj, others)
• Kit 3D (max, dxf)
• WireCase (max, 3ds, dxf, lwo, blend, obj, fbx)
• Amazing3D (max, 3ds)
• Model3D (max, 3ds, arcon, o2c)
• PlanIT 3D (max, 3ds, dxf, lwo)
• The Singularity (3ds, lwo)
• TurboSquid (max, 3ds, oth, obj, lwo, mb)

Presumed Royalty-Free Sites

In fact, this type of site is so common that these may be regarded as the default terms. The following sites are very unspecific about their terms (I could not find any explicit license statement), but it seems safe to assume that the implied license is "royalty free for any use" with no redistribution allowed:

• 3D Plants (3ds)
• Mr Furniture (max, 3ds, dxf)
• Creative-3D (3ds)
• Klicker (3ds, others)
• Digital Animators(max, 3ds, dxf, lwo). Small artist collection. Lot of dead links.
• Cadalyst (max, 3ds, cad, lwo). Site appears inactive (a lot of bit rot).
• Total-3d (max, 3ds, dxf, lwo)

Unacceptable sites

For the sake of completeness (and to help you avoid them), here are the sites I rejected. I also had to throw out five of the sites because they simply don't exist any more, or no longer have free downloads.

Fan-art sites (3 sites)

These sites specialize in artwork which is derivative of other works. In fact, these may be terrific if you are making a fan video animation, and some studios are very supportive of that. However, others are not. Using models from these collections is probably asking for legal trouble if you ever make any money from your project -- not from the site, but from the studios on which the site content is based.

• Sci-Fi 3D(max, 3ds, fbx, lwo). Categories for many different shows.
• Trekmeshes (max, 3ds, cob, lwo). Derived from Star Trek designs.
• 2001 3D Archive (max, 3ds, cob, lwo, lws). Derived from 2001: A Space Odyssey.

Too ambiguous (5 sites)

These sites had such vague license terms that it was impossible to tell whether they allowed free use of renderings. In most cases, there was some contextual reason to suppose they might not be "royalty free for any use". I recommend avoiding these (Corporate Media News, 3d Model Sharing, Rocky3d, DD-Freebies, 3d Auto Club).

Clearly unacceptable terms (14 sites)

These sites claim to restrict even the use of rendered images of the models. I'm not positive that's even legal, but in any case, it certainly is not acceptable for any kind of free culture project. These sites are like hidden bear traps -- they are labeled as "free", but using material from these sites could expose you to legal liabilities and totally derail your project, so I recommend that you AVOID THESE SITES (Apollo Maximus, Large Geometric Models Archive, 3D Faws, 3D Gurukul, 3D Valley, 3d Content Central, 3DAllusions, DMI Car 3D Models, 3D Total, Great Buildings, 3DModelFree, Artist-3D, 3dm3, Dewantoro Network).

Compromises and Snares

Once you venture out of the safe free-trade zone of free-culture projects, things get a bit dicey. But there are circumstances under which it probably makes sense to use "royalty free" work. As I've noted in this article, most of the time, these terms do not place restrictions on the final work. So you can still release under a free Creative Commons license.

If we do this in Lunatics, we'll simply included the rendered video from such elements as a piece of stock footage in the source tree. This will allow the complete film to be re-built, but it won't be possible to edit those sections. I'm probably willing to do this for some shots where the model is something we're unlikey to see again in the series.

But it's a slippery slope. It's hard to draw a particular line, and even harder not to find yourself edging across it. Yet, every time you let in a new restrictive element, the whole production becomes harder to manage. It will be more difficult to have a separate collection of "non-free" models that can't be mixed with the main source tree.

I can't speak for readers, and I'm not even sure for my own project, but I hope this categorization helps you to make your own choices about your own projects.