While visiting the Autodesk Innovations Lab at Singularity University in Mountain View, CA, I designed this in a few hours in a first session with Autodesk Inventor Simulation 2011. It was printed to about 5 cm on a side on a Dimension Printing uPrint printer. The print took about 14 hours.

I am told this design should also print on a Makerbot in about an hour, and they will try that experiment later this week.