I thought of a jewelry idea I did years ago (twenty or more). We used "old"
scraps of colored construction paper. "Tear" into interesting free form
shapes. Start with piece the size you want the finished piece to be. Layer
same and other colors like the strata of rocks. each succesive layer should
be a tiny bit smaller than the one below it. We did this layering with ever
so slightly watered elmer's glue. Works kind of like paper mache, however
the artist carefully controls the colors and shapes. The tearing allows the
pieces to bond more smoothly because of the slightly uneven pulp. The
finished product looks a lot like an agate. You can use an emory board to
smooth outer edge slightly - then be sure to put another layer of elmer's
over all for sheen. You could probably use a acrylic sealer just as well.
We put pin backs on the backs. You can stay very simple or get really wild
with shape and color. Have fun. Linda in OK