Youtube user Ssmallfry demonstrates how to make a really cool penny-covered table.
First the table was sanded down to allow for adhesion of the backer paint. This paint was black to provide a good background for the gaps in the pennies.
Then the pennies were glued down.
Finally the epoxy resin was mixed and poured onto the table. Once allowed to cure, it shows a very nice consistent surface coating of clear resin and copper pennies.