The goal of origami is to create a likeness or representation of an object using geometric crease patterns and fascinating folds. Traditionally, this is done without the use of glue or scissors and general only requires one piece of paper. Modular origami, sometimes also called unit origami, is a relatively new invention in the origami world. This is especially so when you consider that origami has been around for over 1800 years.
There are restrictions that separate unit origami from other forms of multi-piece origami, which includes using several identical copies of any folded unit, and linking them together in a repeating or symmetrical fashion to complete the model. There is a common misconception that abounds that treats all multi-piece origami as unit origami, but this is just not the case. You are allowed to use more than one type of module. Generally, this means using separate linking units hidden from view that hold areas of the construction together. Any other type of usage is typically frowned upon.
The first historical evidence of modular origami design came from a Japanese book published in 1734 by Hayato Ohoka, called “Ranma Zushiki.” It contains an illustration that shows a group of traditional origami units, one of which is a modular cube called the cubical box. The six modules that are required for this design were developed from the traditional Japanese paper fold known as the Menko. Each unit forms one side of the finished cube. The model’s appearance in the 1700s suggests that unit origami remained part of the paper folding tradition, though it is also indicative that not much experimentation had taken place up to that point.
Generally, most traditional designs are a single piece and the possibilities inherent with the unit origami idea were not explored any further until the 1960s, when the technique was re-addressed by Robert Neale in the United States and later by Mitsonobu Sonobe in Japan. Since that time, the unit origami technique has been popularized and developed much more extensively, and now thousands of designs have been developed. Unit origami forms may be flat or three-dimensional. Flat forms are typically origami stars, polygons, rings and rotors.
The actual launch of modern unit origami can be traced to one single invention; the Sonobe Module. Credited to Mitsunobu Sonobe of Japan, it is a module unit bursting with possibility. The design is that of a parallelogram with two tabs and two pockets. Corresponding tabs of corresponding Sonobe units can be inserted into these pockets.
Although Mitsunobu Sonobe is recognized as the architect behind the Sonobe Module, another origami student who took modular origami a step further is Steve Krimball. According to origami historians, it was Krimball of the United States who took the Sonobe unit and developed new ways to build with it. The 1970s brought major breakthroughs in the unit origami world, providing the foundation for all models developed thereafter.