These thermoplastic crystals melt at about 110 °C. They can then be processed into a mass that holds its shape when cooled. After achieving the desired shape, you can let it cool in open air, or place it in ice water to speed up the hardening.
The thermoplast can be re-shaped - just reheat it and you can add more crystals
Caution: Take care when working with the heated thermoplastic, it can easily cause burns.