'Modern Kusudama Origami' by Ekaterina Lukasheva is an excellent book on modular origami. To date I have already tried out 3 models and here is the fourth one - the Jaciara.
For the first attempt, I went ahead with the recommended paper size - 4 inches square. The finished model was about 5 inches in diameter - a tad too big for my liking. The next time I try, I will attempt a much smaller size, probably 2 inches or so.
The individual modules are not too difficult to fold, though it looks kinda scary at first! I liked the way the modules locked together.
There are a couple of variations mentioned. Hopefully I will get a chance to fold those as well.
Model Details:
Model: Jaciara
Creator: Ekaterina Lukasheva
Book: Modern Kusudama Origami
Author: Ekaterina Lukasheva
Difficulty Level: High Intermediate
Paper Ratio: Square
Paper Size: 4 inch squares
Model Size: ~5 inches in diameter
Modules: 30
Tutorial: Youtube