Marble Pocket Stone Craft?

WELL WHAT YOU ARE DESCRIBING IS CALLED A WORRY STONE . THESE STONES ARE CARRIED IN YOUR POCKET AND WHEN YOU ARE WORRIED YOU , HOLD THE STONE AND SORT OF MASSAGE IT AROUND WITH YOUR HAND OR RUB YOUR THUMB AROUND THE TOP OF IT . YOU CAN FIND ANY SMOOTH STONE OUT SIDE CLEAN IT GOOD AND YOU HAVE A WORRY STONE . BUT YOU CAN ALSO PAINT IT OR DRAW ON IT IF YOU PERFER . MY GRANDFATHER HAD ONE WHEN HE DIED HIS STONE WAS SO THIN IT ALMOST HAD A HOLE IN IT . I HAVE ONE THAT WAS JUST A WHITE STONE ROCK IT WAS SMOOTH I RUBED IT FOR A BIT AND WHEN I WAS DONE THE THING HAD TURNED A DARK GRAY .

Could you make one out of polymer clay? You can buy polymer clay at craft stores (Hobby Lobby, Michael's, Joann's). Walmart may carry it too.