Smooth Cast 65D Liquid Plastic Casting Resin - Trial Unit unique gradual cure profile that makes it ideal for rotational casting applications ("roto-cast") in a machine or by hand. Low-cost semi-rigid urethane casting resin Low viscosity for minimal bubble entrapment Semi-rigid plastic has good impact and abrasion resistance Vibrant colors are possible by adding SO-Strong color tints or Ignite color pigments.