Modular origami, also called unit origami, requires two or more pieces of paper. The paper is folded into a shape called a "unit" or a "module". Many units are assembled together to form the final origami model.
Often, the final model looks remarkably different compared to the appearance of the units themselves. Go to Origami Heaven for great information and to Modular Mania for great photos. [Photo: "UVWXYZ" by M. Mukerji].
The best modular origami models have the following features:
- Units are easy to fold
- Units can easily be assembled
- finished model maintains its shape without glue or tape
- finished model is pleasing to the eye.
["FIT" by Tom Hull; photo by E Westcott]
Some units, like the Sonobe unit, are versatile. The number of units used, and the way the units are assembled can change the appearance of the final model. Charles Esseltine's TSU can also be assembled in different ways.
[Photo: "TSU" octahedron by C Esseltine]
Almost all models of this type are polyhedrons, though Nick Robinson has a modular caterpillar and there are many flat models such as stars, wreaths and rings. [Photo: "Traditional Spikey Star"]
Some unit origami diagrams start with A-shape paper. This is the International Standard sized paper that is used all over the world except in USA and Canada. The unique feature of this rectangular sheet is that the height:width ratio is √2:1. Because of this ratio, a sheet of A4 paper (8.25" × 11.7") can be cut in half to give two sheets of A5 which also have a height:width ratio of √2:1. This shape is sometimes called a silver rectangle. You can make A-sized paper from USA letter-sized sheets, or you can buy it.
Image from wikipedia.com.
Whether you are using a A-shape or square piece of paper, it is important that the sheets are EXACT in size. Sheets that are not exact will cause the units to be difficult to assemble. You may wish to get a good paper cutter.