Resin is a two-part epoxy that hardens into a clear coating over whatever you pour it on. You can cast it, imbed objects in it or use a doming technique to make photos into pendants or earrings.
You can cast it into any shape. I have made heart-shaped pendants and encased everything from watch parts to candy sprinkles inside! I have also used it to create a water-like look over polymer, encase Swarovski crystals or even make resin paper.