I just finished designing and building

http://www.thingiverse.com/thing:39789

The pain with enclosed cable chains is you can't easily rewire them or replace a link.

Here I've made a set with a U section instead of enclosed. It is also easier to clip these open links together than the closed ones.

Extras.

I've added some "45-x" part which can bend back 45 degrees as well as forwards.

Likewise the "22-x" is 22.5 degrees and "9-x" is 9 degrees

I've done two versions of the basic link - one with the top open and the other with the bottom open. You can use these to build a chain with the channel on the inner side or the outer side. You can also alternate them to have the the cable somewhat captive.

There is also a groove to hold a zip-tie is place.

My chain has the two lowest movable bottom links reversed compared to the rest.

There are now parts which can bend back so there is no need to do this anymore.