How I draw an empty potato chips bag

To all you fine artists out there...
We just love these kinds of vids! Talk about an amazing skill... Italian illustrator Marcello Barenghi shows off his skills....









Final picture: http://www.marcellobarenghi.com/2013/...
Materials used: http://www.marcellobarenghi.com/p/mat...
It took me: 4 hours and 36 minutes