PaulSage

Here's two I found:

http://www.monroeengineering.com/hin...iano-hinge.htm
http://www.abcplastics.com/index2.ph...s&prod=a_10CBW

Actually, this site has a whole list of plastic hinge mfg's.
http://www.thomasnet.com/products/pl...8240206-1.html

Here's another one that looks pretty cool, but they only come in 12" (apparently...)
http://www.usplastic.com/catalog/pro...uct%5Fid=17534