Hikkake Star
Mondrian Cube
Octahedral Sonobe
Simply put, modular origami is a paperfolding technique that utilizes two or more sheets of paper to create a complex multi-unit structure. Just like normal origami, the use of glues, thread, or any other fastening device is generally considered unacceptable in the building process.
The first historical evidence for modular origami design comes from a Japanese book by Hayato Ohoka published in 1734 called Ranma Zushiki, where a Japanese paperfold commonly known as the menko is used to create a cube.