Blender 3D - Battle Tank

Side view - Wireframe 

Front View - Wireframe

Top View - Wireframe

Camera View - Wireframe

Camera View - Solid

Final Render 

Blender 3D

Blender is an integrated 3d suite for modelling, animation, rendering, post-production, interactive creation and playback (games). Blender has its own particular user interface, which is implemented entirely in OpenGL and designed with speed in mind. Python bindings are available for scripting; import/export features for popular file formats like 3D Studio and Wavefront Obj are implemented as scripts by the community. Stills, animations, models for games or other third party engines and interactive content in the form of a standalone binary and/or a web plug-in are common products of Blender use.
 I'm still new to blender but it's not too hard to learn...and by the way it's free.

Download

The Blender User Manual is also available to download in HTML and PDF format.


Blender interface:

Another screenshot

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Final render images :