Here are some sources of free 3d models from across the web. Take them apart, put them back together, understand what makes them tick, to improve your own modeling.

Blender-Specific

These sites offer .blend files for download.

• The Official Blender Model Repository
• Blender for Architecture
• http://opengameart.org — more Blender models
• http://katorlegaz.com/3d_models/index.php -- they have furniture, arcade video games, joysticks, toys, vehicles, road and sidewalk items, and simple human models
• Yorik’s site — some Blender files for his architectural projects are available for download.
• BlenderKit — free models, materials and brushes available through Blender add-on.

Non-Blender-Specific

These sites offer models in other formats.

• http://archive3d.net - 15,000+ free models from archive 3d

This seems to have some licensed models and might be legal trouble see Discussion at http://blenderartists.org/forum/archive/index.php/t-237569.html

• http://sketchup.google.com/3dwarehouse/ - Google's 3d warehouse repository; take the collada version, when available ( the Google Earth downloads are actually .zip files with a collada inside them, so just rename and unzip)

Note: some of the 3d warehouse models can't be understood by blender due to a zillion repeating elements, others will show up invisible (one sided, or inside out), be gigantic in size, or all parented to some crazy spot out in space. Fixing these to be usable will push your blender skills to new levels in some cases.

Tips: I’ve tried importing a few of these 3D Warehouse models, and so far I’ve only noticed a couple of issues:

• • The model imports into a new Blender scene, called something like “SketchupScene” or “SketchupScene001”. You may also find additional scenes created with nothing in them, that you can delete. If you try rendering, you may not see anything, because the default camera is only linked into the original default scene named “Scene”. Just select the camera and hit CTRL+LKEY to link it into the new scene.
  • You may notice parts of the model appearing and disappearing as you try viewing it from different angles. This is because it is scaled very large (several hundred Blender Units on a side). Try scaling it down so it’s no more than a few BU on a side.
  • There will usually be a lot of doubles, so remove them with WKEY->remove doubles.
  • There may be many separate objects, so select what you want to combine and hit CTRL+J to join them all into one object.

• https://www.stlfinder.com - The free 3d model search engine
• https://www.yobi3d.com - 3D model search engine with previews in 3D
• http://free3dbase.com/ - furniture models without registering
• http://artist-3d.com/ - wide variety of free models
• http://nasa3d.arc.nasa.gov/ - all kinds of free models from the space program
• http://www.3dm3.com/modelsbank/ - around 300 free models
• http://www.amazing3d.com/free/free.html - free section on amazing 3d about 75 models of all kinds of things.
• http://www.corporatemedianews.com/2002/03_mar/features/3dmodellibrary.htm - free models from corporate media news; a very interesting collection from klingon space ships to footballs.
• http://3dplants.0catch.com/download.html - about 70 free 3d plant models
• http://www.3delicious.net - 3d delicious, lots of models, but way too many popover ads! (click the picture, then click the bigger preview in the next page to download)
• http://www.top3dmodels.com/products/3d-models/free - 20 free models
• http://www.top3d.net/free-3d-models/ - about 85 models, including washing machines, tires, and jewelry
• http://www.oyonale.com/modeles.php?lang=en&format=OBJ - about 17 free models form guns, to rubber duckies
• http://dmi3d.comeze.com/ - a few hundred free models of cars, race cars, trucks, tanks, backhoes, etc.
• http://www.scifi3d.com/list.asp?intGenreID=14&intCatID=36 - free models of scfi empires like, Aliens, Babylon5, Blade Runner, BS Galactica, Original SciFi, Other SciFi, Star Trek, Star Wars
• resources.blogscopia.com - models in Blender and other formats.
• http://www.hobbycncart.com/ - Free relief models (all modells are free) in .STL .OBJ and depth map (.BMP) formats.
• http://www.craftsmanspace.com/free-3d-models - Free 3D models (Creative common licenses) in .STEP, .IGES, .STL .OBJ and .BLEND formats.
• http://tf3dm.com — models in various common formats, including some in .blend; can be downloaded without registration (subject to slight delay). However, most seem to be under “personal use only” or “non-commercial use” licences.