Very good strings can be made from rawhide, but make sure the width is even. The string is only as strong as its weakest point.
You can make arrowheads out of bone. Shape, and sharpen. Haft, and secure. Just don't breath in the dust! Wear a face mask, and shape/sharpen in a well ventilated area, if not outside. Antler also makes a decent arrowhead, though it is difficult to get to a legal width sometimes (most states have a requirement of at least 7/8 inch, and some have material requirement). Have fun!