Slim-Z-Coupling

There are countless Z-Coupling for 3D-Printer: rigid, flexible, printable and other variations. I'm using the Slim-Z-Coupling for a couple of weeks and I thought it's mature to propose this solution.

Features:
- Slim and light.
- No need of screws.
- The Slim-Z-Coupling is rigid in the radial but flexible int axial-direction.
- Easy to build with simple tools.
- Using the Z-Support-Bracket ( http://www.thingiverse.com/thing:52388 ) you can reduce the force on the motor-shaft.
- It reduc