Now we need to mix up some putty. This is made from ground up leather ( leather  dust) mixed with rubber cement. Put some leather dust into a bowl or jar or similar container and then pour rubber cement in with it. Mix this up to the consistency of  peanut butter.  Then spread the mixture onto the back of your buffalo, trying to stay inside the lines we drew with the pen. Build it up until it is about a quarter inch higher than the leather.