UPDATE: I have made a customizable version of this thing: http://www.thingiverse.com/thing:73634

Enjoy!

I improved tolerances and parameterized the OpenSCAD of the derived project. Parameters: Number of rings, thickness of rings, ring width, spacing between rings, pin radius, center hole size.

Now the pins are printed resting on the hole of the next ring providing natural support and better shaped pins. To allow this and keep the pins centered, each ring is slightly thicker than the previous.