Some more uses...

At Michael's craft store you can buy a card of six neodymium magnets that are exactly 1/4" diameter. This means that flat-bottomed depressions to receive these magnets can be drilled in material using nothing more than a 1/4" endmill. I made aluminum soft jaws for several of my vises and used this trick to mount magnets on the reverse side so they would stick to the vise jaws.

I have several of those articulated lights with the built-in circular magnifying lens. I discovered that a circular car wax applicator was a perfect fit so I use one for a dust cover for the lens. When I need to use the lens, I don't want to lay the cover in the workbench grunge so I glued a magnet to the material and now I can just stick it on one of the articulating arms. It remains clean and is right to hand when I want to replace it.

Glue a magnet to the corner of a shop towel and you can throw it at any ferrous surface and it will stick. If you use super-glue, you can rescue the magnet when discarding the towel by soaking in a little acetone.

These magnets from Harbor Freight...

https://www.harborfreight.com/10-pie...ets-67488.html

are cheap and scary strong. They're about 7 mm diameter.