Polycaprolactone

From Interlock Rochester Wiki

Polycaprolactone is a low-melting, hand-workable, polyester thermoplastic sold under various brand names such as Friendly Plastic, Instamorph, and Polymorph.

At working temperatures, it is clear and colorless with a stretchable, putty-like consistency. At room temperature it is opaque white, tough, and rigid. Thin cross-section pieces have some flexibility, and it can be drawn out or formed into flexible rods, threads, sheets, or other structures.

Amongst domestic small-quantity suppliers, Sparkfun seems to have the best prices:

Deejoe mostly uses it in Interlock contexts as a hands-on conversation starter for other thermoplastic projects, namely 3DPrinting.

http://interlockroc.org/2012/03/21/quick-open-house-recap/

http://interlockroc.org/2011/12/01/dashing-through-the-thermoplastic-2/