If you've played Ninja games or watched similar anime, you might recognize this. I've always wanted one but have surprisingly not been able to find a file for one, so I designed it myself. The blades will lock into the open or closed position with a firm push and should stay in place even if the whole thing is being swung around.

To assemble, slide the four blades into the slot on the bottom half of the ring. The curved section of the blades should face upward. Then slide the top half onto the blades. this might require some pressure but so far, I haven't had to worry about breaking any of the parts or anything.

From that stage, you should be able to slightly pull the halves of the ring apart without the whole thing coming apart, so you can carefully glue it together. I do so one side at a time, so I can make sure that the slots are aligned well.