ShapeLock is actually polycaprolactone, I think, an extremely shatterproof biodegradable, bioimplantable, anti-static (? or is that only Mater-Bi?) thermoplastic with a melting point around 60°C and a relatively low price. It’s weak, though, and quite viscous when melted.
Tradenames are Mater-BiZ (a mixture of polycaprolactone and starch), Anderson Andur 6 APLM, Boltaron 4300, and Dow Tone P-767 or P-787. See http://www.ides.com/grades/Boltaron_grades.htm and related pages.
There is some pricing in the RepRap blog comments: http://blog.reprap.org/2005/12/polymorph-and-polycaprolactone.html says “$5.30-3.50/lb for CAPA 6800”. It also gives the name “CAPA 6800 polycaprolactone (2-Oxepanone, homopolymer; molecular weight 80,000, CAS number: 24980-41-4)”.
The blog post suggests Solvay Interox Ltd. as a supplier. In early 2008, they were sold to the Perstorp Group of Sweden. CAPA was Solvay’s brand. Now it is http://www.perstorpcaprolactones.com/; they claim to be a “global supplier”.
http://reprap.org/bin/view/Main/Polymorph says Solvay’s product cost US$9/kg in 20kg or 500kg bags.
By comparison, Forrest Higgs says:
Right now you can buy HDPE filament for about $4.50/lb. ABS costs about a dollar per pound more, if I remember correctly. That means that the filament to make the printed parts for a Darwin will cost you about $12.50 while for a Tommelise the cost will be closer to $30.
There’s another blog post on the topic at http://createdigitalmusic.com/2006/08/29/prototyping-custom-gear-friendly-plastic-aka-shapelock/ that says it’s hard to find the stuff in Australia.
Someone suggested Consilium Designs, an eBay merchant that sells many specialty substances. http://www.mutr.co.uk/ is another UK company that carries essentially the same items.
According to Perstorp’s datasheet, their product crystallizes at 25°C, has a glass transition temperature at 60°C, and has 77 joules per gram heat of fusion, more or less. And it supercools. Yield stress is around 16±1MPa, modulus is around 470±30MPa, and strain at break is >700%.
When melted, the higher molecular weight polycaprolactones are 4x as viscous as the lower molecular weight ones, but they all decrease in viscosity by another factor of 6 or so when heated to 150°C.
It’s very permeable to CO₂, water, and oxygen.
One person reported that polycaprolactone is better than HDPE for FDM accuracy at great length; it warps less, has less “die swell” (that is, the molten filament isn’t much bigger than the extruding hole), sticks to more things, and is “more compliant” (??). But it has a lot of other problems. http://hydraraptor.blogspot.com/2008/03/chalk-and-cheese.html