auto cad and pro-e is easy software for 3d modelling and u can download crack version from torrent and it is easy to install.

The free version from Sketchup (http://www.sketchup.com/) would be a good choice for beginning. If you need more sophisticated modeling there is also Blender (https://www.blender.org/).

But from the attached picture, Sketchup should be very well suited for the task.

Vishal, I don;t think advising people downloading license protected software from p2p network is a wise thing. this is actually stupid thing to do, since it is not legal.

Anil, have a look at http://www.freecadweb.org/ 

Thank you all for your valuable suggestion.

Just as René suggested earlier, Blender is a good solution if you ever need more than simple "Lego" variant of 3D "modelling".

Dear Milan Tair, thank you. I have to try with one out of sketchup, blender, Lego and also available at freecad.org . I have downloaded sketchup pro suggested by Mr. Rene, but it has only one month validity.

Sketchup Pro is the commercial version, the free version (for non-commercial use) is Sketchup Make.

If you're fond of programming, perhaps OpenSCAD would work for you:

http://www.openscad.org

Dear Paul Lubos,

Thank you for your suggestion. But it would take time if I proceed by programming. I want to make in a small time span. Like I have made through Power point presentation. 

You can make various images in a short time with OpenSCAD. But instead of using a graphical user interface you just write something like:

cube([2,3,4]);

Just another suggestion, as I know that graphical 3D modelling tools can be daunting at first.

https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/First_Steps/Creating_a_simple_model

Anil,

No problems.  Autodesk has three academic suites available for free, with a three-year license, including AutoCAD for mechanical, architectural, and Maya for entertainment content.  Simply navigate to http://www.autodesk.com/education/home, fill out a form using an institutional email alias, activate the account, download, and install the software (have a GOOD network connection - we're talking about 14gb of downloads).  If you're going with the Entertainment Creation Suite Ultimate, you might also want to get the free academic version of Renderman from Pixar.  It needs the Maya front-end but the rendering is awesome.  Bottom line:  thousands of dollars worth of free software for the academic community and almost any platform.

Inkscape for 2D and Blender for 3D pictures.

Blender for animations

For instance: https://www.youtube.com/watch?v=RasemoYzsFA

Blender is a free 3D modeling software, you can try that. There is also google sketch-up simpler to learn but basic tooling.