Last question about this topic.
What leather, animal…, is used to making the bag?
And if i can, What thickness(of leather).
What? Are you bag again? 
There are many choices, because there are so many different types of bagpipes out there on the market already. My L&M is made of sheepskin, approx 2mm, sewn with an additional leather binding strip. There are also synthetic bags available.
As I recall, you said you are in Spain. Do you have access to these folks:
http://www.arhpa.com/ingles/flash/index.htm
Perhaps they can help you as well.
djm