Mitsonobu Sonobè's module is an excellent one for beginners and experts alike. Literally dozens of models are possible and the workshop format allows each student to learn the one(s) they like. Good for those looking for an introduction to modular origami as well as those looking for more of a challenge. Models made from 1 to 60 modules will be shown. Construction ranges from low intermediate up to challenging. The basic module and some variations will be presented.
Many places, including Paperfolding for Fun by Eric Kenneway, p. 64; Origami for the Connoisseur by Kashahara and Takahama, pp.42ff; many diagrams and videos on the internet.