Have you heard of sea glass? It is glass from ordinary man made objects like bottles, glasses and such that has been tumbled by the waves of the sea to take the sharp edges out of it and appears like a gem of sorts.
What about sea plastic? Unlike glass which can weather and deteriorate with time plastic lasts much longer and retains much of it's original shape and colors. What do you do with the plastic stuff you find along a beach? Here's a great article on some folks that are making art out of found plastic items from beaches. If you'd like to see some examples look here.
Until my next post,