This is probably one of the most asked questions. The answer, a file, and a sharpening stone. Thats it, just that simple. File a piece of steel to the desired shape and sharpen it with the stone. That is making a knife at its most simple form. Actually, and more realistically you need a file to shape the knife and to shape the blade bevels. You need a heat source to heat treat and temper the knife and you need a drill or drill press to drill holes. These things and some sandpaper and epoxy and you can make a very nice knife. You can really go nuts buying tools but these are the only MUST HAVE tools.