The STL represents the hinges as thin regions, about 0.2mm thick, aligned with either the top surface or bottom surface depending upon which way a particular hinge is supposed to be folded. The entire model is only 3 layers thick when built on the SD300, so I built one model using a different color material for each layer so the hinges appear in different colors (red or blue) depending on which way they're supposed to fold.
I uploaded the data to Thingiverse (here) but most hobbyists won't be able to build in with homebrew 3D printers so I designed a model that would act as a template to help someone cut and fold a similar twirling model from heavy paper.
A sheet of paper would be sandwiched inside the template, the rings are cut by pushing a knife through the grooves, and the folds are embossed by applying pressure.
But the cuts aren't very clean so the paper model didn't work very well.
Even so, I uploaded the template model to Thingiverse so other users can try it...and maybe improve it. In the meantime I'm satisfied with the SD300's plastic version, which works nicely.
I wonder if it could be scaled down to business-card size...
