A Ninja Star or Shrunken is a throwing weapon that ninjas used in combat. It was designed, so that however you throw it, it will always hit a blade; making for a deadly weapon. I liked the sound of that so I decided I would make my own. They are very easy to make and use and you can customise them greatly to suit you. If you are wanting to quickly make one to throw into cardboard or as a prop you can use aluminium but if you want a sharper heavier star, try using mild steel or high carbon steel. Also you can make these using only files and a hacksaw

(Just like the first one I made) or for speed use an angel grinder and a belt sander, if you have one.