How to draw a 3D snail

How to draw a 3D snail with mixed media on gray paper. 3D drawing by Marcello Barenghi http://www.marcellobarenghi.com
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Drawing a realistic snail, materials used are listed below :)
Final picture: http://www.marcellobarenghi.com/2013/05/drawing-snail.html
Materials used: http://www.marcellobarenghi.com/p/materials-used-for-my-drawing-video-on.html
It took me 2 hours and 36 minutes
Music: "Undiscovered Oceans" by Dan-O at http://danosongs.com ("Package" Licence)
http://www.danosongs.com/music..../danosongs.com-undis