Check out info on resin casting. You have a mold, mix the resin with a catalyst. Whatever is in the mold gets embedded in plastic. - This link doesn't include info, but it's a reminder to go check out more info on resin casting
ALYCE SANTORO: SONIC FABRIC, the invention of sound and conceptual artist Alyce Santoro,is a beautiful, audible, versatile textile woven from polyester thread and audiocassette tape recorded with intricate collages of sound.