-flat glass marbles - jumbo sized, clear. I had to order these online, but I once saw them at the dollar store, so if you have time check around. They are usually used in glass vases with flowers.
-decorative paper or photos. old wrapping paper works great. For the photos I printed a bunch on the proof sheet setting of my printer, I think it was 36 photos to a page. that got the faces to be a good size to fit in the marble.
-flat craft/paint brush
-hot glue gun and glue
Place marble flat side down on paper or photo and move around until desired view.
Trace the marble.
cut out inside pencil mark.spread decoupage medium liberally on cut out paper/photo.
press paper/photo on flat side of marble.
apply decoupage medium to back side of paper/photo
apply a liberal dollop of hot glue in middle of flat side of marble
press round magnet in hot glue
We set up a sort of assembly line to make multiple magnets. We cut out multiple paper/photos, decoupaged them all at once. Then I handled the glue gun while my son planted the magnets. One hint is to be sure to put enough glue to come around the sides of the magnet, otherwise the magnet eventually falls off.