Learn to "tan" deer hides and other animal hides the traditional way- no synthetic or hazardous chemicals.  Sometimes called "brain tanning," the process of making traditional buckskin only requires a few easily obtainable items and a little bit of sweat.  In the end, you'll have one of the highest quality garment-making materials known to man.  If you're a hunter, and you hate seeing all of your deer hides go to waste, this is the answer.