Modular origami consists in folding basis models, bricks that are usually identical, in order to assembly them to make a more complex model.
Modular origami lets you create several geometric models or, in experiment hands like Tomoko Fuse's ones, create a very important number of boxes.
This is an example of modular geometric origami :
Another example :
source : Issei Super Complex Origami by Issei Yoshino