Just wanted to share this here, since its stupid simple and I haven't really seen anyone else do it this way. I'll leave it to you to figure out which bolt size works best for you, I'm using a 3/8" bolt.

Preparation time: 5 minutes

Ingredients:

1x Bolt
1x Nut for Bolt
1x Circular Magnet
2x Plastic Washers (Can be 3D Printed)
Superglue to taste
CA Accelerant (Optional)

Step 1: Take the bolt and sand down the top. I did this on a bench sander, but it could easily be done with a file or sandpaper. A nice flat top free of markings will help the bolt adhere to the magnet.

Step 2: Glue the top of the bolt head to the magnet.

Step 3: Glue one plastic washer onto the nut.

Step 4: Glue the other plastic washer to the bottom of the bolt head.

Step 5: Thread the nut onto the bolt, it should spin freely. If needed, a little tiny bit of lubricant can be applied to the inside of the nut.

Enjoy on the metal plate of your choice (magnetic)