Armando, find a glass company and check out their dumpster. 1/4" plate glass works well. In lots of restaurant landscaping there are excellent hammer stones. You don't want real hard rocks for hammer stones. People that install copper gutters and down spouts use copper nails and spikes. These work well for pressure flakers and Ishi sticks. A fine pointed copper nail makes a good notching tool. You can also do all of your pressure flaking with antler and bone. Pat