I'm sure it can be done in Blender, but I have no experience of that. You might also try out Sculptris. That looks pretty useful for organic modelling. It's going to be pretty high-poly though.
http://pixologic.com/sculptris/

More useful might be the free open-source subdivision modeller Wings3D
http://www.wings3d.com/

As for SketchUp, I can't think of any free smoothing plugin to get that final smooth effect, but Joint Push Pull is free/donate. To subdivide the mesh, it is possible to use the free Fractal Erode plugin with iterations set to 1 and the pointyness set to 0

Tig has written a dual dim tool for SU... does everyone here know that?

http://sketchucation.com/forums/viewtopic.php?f=323%26amp;t=62033

Oh ya, my content is quite far from the origin. I did not purposely do it but just randomly develop this drawings from some old drawing. Thanks for giving me the advice.

I have the 2014 package with me, but when I model in Sketchup I prefer using Sketchup 8 as it is more handy and I have less plugin with it, which can make my computer faster.

Thank you very much!

How is made the material? Also have you checked the model? (no backfaces, no smooth etc.)?
Here is a SS of a correct mirror material.
Cattura.JPG

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