A scrap piece of banak, was shaped like a "pin" at the wood lathe, and a neodymium magnet was epoxied at the base.
It is useful for placing shopping lists or messages on the fridge.
At the shop, you could place a blueprint, a cutting list, a chart, a model for woodturning, or even the apron, goggles, earplugs, etc. on any metal surface. On a wooden surface you could insert or just glue a washer or other magnet to hold the pin.