The initial idea came from this project, which was put together in about 15 minutes during our open electronics night: 

The main issue was that this video demonstrates the full range of motion available - twitching left and right with a bit of up and down.  The sync to the music was a result of tuning the speed of the servo manually.

Improvements discussed & kicked about included plugs of some sort to limit the cable movement inside the body, an LED in the eye, motion sensors, etc.

rev1

Used metal shower line - connects wall water to shower head.  Contains internal flexible rubber tube to contain water.  Using the rubber tube to provide internal extension, then steel leader wire to pull down on sides.  Attempted to use segments of heat shrink tubing as guides for the wire to limit cable movement within body.

Note: do not hot glue heat shrink tubing in place.  Again.

Hard to keep wires aligned when positioning guides, should use something like bamboo skewers to hold in place (too large, something smaller).

Original rubber tube has curve, affecting position.

Metal is cool, but how about plastic - could 3d printed segments snap together?  Or one of the nanotubes, somehow cast in oogoo?

rev2

Oogoo experiments.  This stuff really stinks.

Cast a tube using some spare bits.  Solid, not enough flex.  Leader wire will wear through - needs embedded solid anchors, but I think anything embedded will work its way loose.

Oogoo will, however, work great for any eyeballs, flower petals, etc on the top.

For consideration:

http://www.thingiverse.com/thing:54862

http://www.thingiverse.com/thing:44198

http://www.thingiverse.com/thing:13266

http://www.thingiverse.com/thing:351813