Agate Magnets
I'm not sure if these pieces are actually geodes, druzies, or agates. I find them on eBay under searches using all of those keywords so it's never really been clear. I know that geodes have little mineral formations/crystals etc. and some of the pieces I'm using may or may not fall under the agate name used, but because I can't find a definite answer, I'm going with "agate".
These are great easy to make magnets. They make wonderful gifts and are very pretty.
BoM
Agate slices (I get mine from eBay)
Magnets (craft store)
Epoxy/glue
Metallic paint & brushes (craft store)
Paint
Carefully paint the edges of the slice and allow to dry. Depending on the piece, you may want to paint the back as well but this is optional.
Glue
When your slice is dry, glue the magnet to the back and allow to dry/cure fully before use. Some of my magnets are self-adhesive and I still put epoxy on them.