Take a look at PEX Al PEX. It has an aluminum layer sandwiched in between two layers of pex. It's bendable, retains it's shape and strong. Of course you get to pay for all those awesome features but for some applications it's awesome.
PEX-AL-PEX - Aluminum PEX - PEX-Aluminum-PEX - PexSupply.com
While you have your wallet out take a look at these:
they come in a number of configurations and are the future
