Caprolactone Thermoplastic - tongue-twisting mouthful of chemicalness. But this stuff is cool! You have to heat it up to work with it. Paradoxically, it still very cool, believe me.
Caprolactone Thermoplastic (also commonly called ShapeLock, Friendly Plastic, Instamorph or Polymorph) is a biodegradable polyester plastic with a low melting point of around 60°C. When solid it has physical properties of a very tough, nylon-like plastic, but it will melt into a putty-like consistency at only 60°C. It's specific heat and conductivity are low enough that it is not hard to handle at this temperature. This makes it ideal for small-scale modeling, part fabrication, repair of plastic objects, and rapid prototyping where heat resistance is not needed. Though molten caprolactone readily sticks to many other plastics, if the surface is cooled, the stickiness can be minimized while still leaving the mass pliable.
An easy way that we recommend to shape this Thermoplastic is to heat up some water close to boiling and toss the granules in. When they become close to clear in color fish them out (NOT WITH YOUR FINGERS!!!) with a spoon or other such sacrificial item. Wait a little until they cool down a bit and then start shaping it all with your hands (maybe use some gloves if it's too hot). If you'd like to re-shape it, just toss the plastic in the water and try again!
Note: Please read safety instructions (Documentation tab) before using this material.