modular origami: transforming the Japanese pinwheel into a Sonobe unit

In Other models on January 14, 2012 by romi

I made this cube model using six (6) units of the traditional Japanese pinwheel which I folded into Sonobe units. Attributed to Mitsunobu Sonobe in the 70s, the Sonobe unit is a very popular building block in modular origami and a lot of polyhedron models based on it, as well as instructions and diagrams on how to fold the unit, is found in the Internet.

The Sonobe unit has the shape of a parallelogram which is typically folded from a square paper starting with the cupboard base. On the other hand, the traditional pinwheel model as shown below may be viewed as a double parallelogram: one horizontal and one vertical.

By making the upper and lower flaps of the pinwheel ‘disappear’, we are able to transform it into a Sonobe unit. And there are many ways to do this. Here are three pinwheel-turned-Sonobe units:





The models I assembled corresponding with these units are shown below, the last of which is the same model shown at the top of this page. The first, which is called ‘Toshie’s jewel’ or ‘Crane egg’, is made up of three (3) units.


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