K-3D is a free modeling, animation and rendering system available for multiple platforms. K-3D requires a seperate renderer to actually create the image.

K-3D has some very impressive features: ( copied from the website)

• Record interactive tutorials and macros.
• Unlimited undos / redos.
• Create and edit documents in multiple realtime OpenGL solid, shaded, texture-mapped views.
• Scripting interface supports JavaScript and Python, with an open API for other scripting languages.
• Model, animate, and interact with animations while they play back for maximum productivity.
• Highly-evolved architecture allows complete extensibility at runtime through third-party plugins.
• Animated geometric procedural effects.
• Powerful control-spline based animation in a uniform interface.
• Uses the Pixar Renderman Interface to render motion-picture-quality images with a wide variety of rendering engines.
• Supports Renderman Subdivision Mesh output.
• Background rendering and batch rendering.

K-3D does require a seperate renderer, unlike for example Blender 3D, for creating the final images. But this is not a bad thing as K-3D supports the Pixar Renderman Interface (think Toy Story) which is an industry standard renderer. Currently K-3D reccommend th use of the Aqsis renderer.