I used this project (https://www.printables.com/model/785291-naruto-shuriken) as a base and remixed it to use as a magnet. The hole is for 6mm x 2mm magnets.
I'll update the project with new file for different variations of the shuriken.
The author remixed this model.
I slice it and add a hole for a magnet 6mm x 2mm to used it as a magnet.